{ "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-2026-33315", "tracking": { "current_release_date": "2026-03-26T00:50:51.503304Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-33315", "initial_release_date": "2026-03-20T19:55:15.212565Z", "revision_history": [ { "date": "2026-03-20T19:55:15.212565Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)." }, { "date": "2026-03-20T19:55:17.853408Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-24T20:50:56.519135Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-24T20:51:00.257573Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-24T20:51:14.970223Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (3).| CWES updated (1)." }, { "date": "2026-03-24T20:51:24.958520Z", "number": "6", "summary": "Unknown change." }, { "date": "2026-03-24T20:51:29.771160Z", "number": "7", "summary": "NCSC Score updated." }, { "date": "2026-03-24T20:51:34.946193Z", "number": "8", "summary": "References created (1)." }, { "date": "2026-03-24T20:53:29.703958Z", "number": "9", "summary": "CVSS created.| Products connected (1).| Product Identifiers created (1).| Exploits created (1)." }, { "date": "2026-03-24T20:53:32.268698Z", "number": "10", "summary": "NCSC Score updated." }, { "date": "2026-03-24T21:19:13.336562Z", "number": "11", "summary": "NCSC Score updated." }, { "date": "2026-03-25T18:13:07.593923Z", "number": "12", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (2).| CWES updated (1)." }, { "date": "2026-03-25T18:13:10.287734Z", "number": "13", "summary": "NCSC Score updated." }, { "date": "2026-03-25T18:13:41.785640Z", "number": "14", "summary": "Source created.| CVE status created. (valid)| Description created for source.| References created (2)." }, { "date": "2026-03-25T21:50:19.722892Z", "number": "15", "summary": "References created (2)." }, { "date": "2026-03-26T00:13:01.933384Z", "number": "16", "summary": "References created (2)." }, { "date": "2026-03-26T00:50:35.380724Z", "number": "17", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-26T00:50:39.880335Z", "number": "18", "summary": "NCSC Score updated." } ], "status": "interim", "version": "18" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/>=0|<=2.1.0", "product": { "name": "vers:unknown/>=0|<=2.1.0", "product_id": "CSAFPID-5907212" } } ], "category": "product_name", "name": "api" }, { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<2.2.0", "product": { "name": "vers:unknown/<2.2.0", "product_id": "CSAFPID-5902485" } } ], "category": "product_name", "name": "vikunja" } ], "category": "vendor", "name": "go-vikunja" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<2.2.0", "product": { "name": "vers:unknown/<2.2.0", "product_id": "CSAFPID-5902768", "product_identification_helper": { "cpe": "cpe:2.3:a:vikunja:vikunja:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "vikunja" } ], "category": "vendor", "name": "vikunja" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-33315", "cwe": { "id": "CWE-288", "name": "Authentication Bypass Using an Alternate Path or Channel" }, "notes": [ { "category": "description", "text": "### Summary\nThe Caldav endpoint allows login using Basic Authentication, which in turn allows users to bypass the TOTP on 2FA-enabled accounts. The user can then access standard project information that would normally be protected behind 2FA (if enabled), such as project name, description, etc.\n\n### Details\nThe two files below show that when a user is accessing Caldav via Basic Authentication, it skips all steps involving 2FA. The order of operations is essentially:\n1. Retrieve basic credentials.\n2. Verify username.\n3. Verify password.\n4. Success\n\n**pkg/routes/caldav/auth.go:45**\n```go\nu, err := checkUserCaldavTokens(s, credentials)\n\tif user.IsErrUserDoesNotExist(err) {\n\t\treturn false, nil\n\t}\n\tif u == nil {\n\t\tu, err = user.CheckUserCredentials(s, credentials)\n\t\tif err != nil {\n\t\t\tlog.Errorf(\"Error during basic auth for caldav: %v\", err)\n\t\t\treturn false, nil\n\t\t}\n\t}\n```\n\n**pkg/user/user.go:358**\n```go\nfunc CheckUserCredentials(s *xorm.Session, u *Login) (*User, error) {\n\t// Check if we have any credentials\n\tif u.Password == \"\" || u.Username == \"\" {\n\t\treturn nil, ErrNoUsernamePassword{}\n\t}\n\n\t// Check if the user exists\n\tuser, err := getUserByUsernameOrEmail(s, u.Username)\n\tif err != nil {\n\t\t// hashing the password takes a long time, so we hash something to not make it clear if the username was wrong\n\t\t_, _ = bcrypt.GenerateFromPassword([]byte(u.Username), 14)\n\t\treturn nil, ErrWrongUsernameOrPassword{}\n\t}\n\n\tif user.Issuer != IssuerLocal {\n\t\treturn user, &ErrAccountIsNotLocal{UserID: user.ID}\n\t}\n\n\t// The user is invalid if they need to verify their email address\n\tif user.Status == StatusEmailConfirmationRequired {\n\t\treturn &User{}, ErrEmailNotConfirmed{UserID: user.ID}\n\t}\n\n\t// Check the users password\n\terr = CheckUserPassword(user, u.Password)\n\tif err != nil {\n\t\tif IsErrWrongUsernameOrPassword(err) {\n\t\t\thandleFailedPassword(user)\n\t\t}\n\t\treturn user, err\n\t}\n\n\treturn user, nil\n}\n```\n\n### PoC\n1. Setup a Docker instance of Vikunja `v2.1.0` and create an account. Enable 2FA on the account.\n\"CleanShot\n\n2. Logout of the account.\n3. Using a web proxy, such as Burp Suite, craft an HTTP request to the endpoint similar to the one shown below. Ensure that the 2FA-enabled user's username and password is properly Base64-encoded and inserted into the `Authorization` header.\n\n```http\nPROPFIND /dav/principals/ HTTP/1.1\nHost: 127.0.0.1:3456\nAuthorization: Basic {{ REDACTED }}\n[ TRUNCATED ]\n\n\n```\n5. Observe that the response contains authenticated user information.\n```http\nHTTP/1.1 207 Multi-Status\nContent-Type: text/xml; charset=utf-8\nVary: Accept-Encoding\nDate: Mon, 16 Mar 2026 19:31:47 GMT\nContent-Length: 398\n\n/dav/projectsprojects\n[ TRUNCATED ]\n```\n6. Other requests can then be crafted to retrieve more information about a specific project, such as the one below.\n```http\nPROPFIND /dav/projects/1/{{ PROJECT NAME }}/ HTTP/1.1\nHost: 127.0.0.1:3456\nAuthorization: Basic [ REDACTED ]\n[TRUNCATED]\n\n\n```\n\n```http\nHTTP/1.1 207 Multi-Status\nContent-Type: text/xml; charset=utf-8\n[ TRUNCATED ]\n\n[ TRUNCATED ]\nBEGIN:VCALENDAR VERSION:2.0 X-PUBLISHED-TTL:PT4H X-WR-CALNAME:Inbox PRODID:-//Vikunja Todo App//EN BEGIN:VTODO UID:8gb6eclz-dad5-4a38-80a8-09005707eb51 DTSTAMP:20260316T190905Z SUMMARY:test DESCRIPTION:<p>description</p> CREATED:20260301T203712Z LAST-MODIFIED:20260316T190905Z BEGIN:VALARM TRIGGER;VALUE=DATE-TIME:20260316T130000Z ACTION:DISPLAY DESCRIPTION:test END:VALARM END:VTODO END:VCALENDARHTTP/1.1 200 OK\n[ TRUNCATED ]\n```\n\n### Impact\nAny user that has 2FA enabled could have it bypassed, allowing attacker access to a lot of the user's project information. \n\n### Remediation\nIf there are 2FA barriers to access an account in a specific fashion, all integrations should follow those if they're using the same methods of authentication. The easiest path is probably to disable Basic Authentication for Caldav by default, but keep the token access enabled, that way users can generate tokens specifically for Caldav if they want to use that feature. Basic Auth for it could be kept, but would most likely want to be a feature flag or something along those lines. That's so users can turn it on if it's necessary, but can be notified in the documentation that it's a more unsafe pattern if 2FA is enabled.", "title": "github - https://api.github.com/advisories/GHSA-47cr-f226-r4pq" }, { "category": "description", "text": "Vikunja is an open-source self-hosted task management platform. Prior to version 2.2.0, the Caldav endpoint allows login using Basic Authentication, which in turn allows users to bypass the TOTP on 2FA-enabled accounts. The user can then access standard project information that would normally be protected behind 2FA (if enabled), such as project name, description, etc. Version 2.2.0 patches the issue.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33315" }, { "category": "description", "text": "Vikunja is an open-source self-hosted task management platform. Prior to version 2.2.0, the Caldav endpoint allows login using Basic Authentication, which in turn allows users to bypass the TOTP on 2FA-enabled accounts. The user can then access standard project information that would normally be protected behind 2FA (if enabled), such as project name, description, etc. Version 2.2.0 patches the issue.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33315.json" }, { "category": "description", "text": "### Summary\nThe Caldav endpoint allows login using Basic Authentication, which in turn allows users to bypass the TOTP on 2FA-enabled accounts. The user can then access standard project information that would normally be protected behind 2FA (if enabled), such as project name, description, etc.\n\n### Details\nThe two files below show that when a user is accessing Caldav via Basic Authentication, it skips all steps involving 2FA. The order of operations is essentially:\n1. Retrieve basic credentials.\n2. Verify username.\n3. Verify password.\n4. Success\n\n**pkg/routes/caldav/auth.go:45**\n```go\nu, err := checkUserCaldavTokens(s, credentials)\n\tif user.IsErrUserDoesNotExist(err) {\n\t\treturn false, nil\n\t}\n\tif u == nil {\n\t\tu, err = user.CheckUserCredentials(s, credentials)\n\t\tif err != nil {\n\t\t\tlog.Errorf(\"Error during basic auth for caldav: %v\", err)\n\t\t\treturn false, nil\n\t\t}\n\t}\n```\n\n**pkg/user/user.go:358**\n```go\nfunc CheckUserCredentials(s *xorm.Session, u *Login) (*User, error) {\n\t// Check if we have any credentials\n\tif u.Password == \"\" || u.Username == \"\" {\n\t\treturn nil, ErrNoUsernamePassword{}\n\t}\n\n\t// Check if the user exists\n\tuser, err := getUserByUsernameOrEmail(s, u.Username)\n\tif err != nil {\n\t\t// hashing the password takes a long time, so we hash something to not make it clear if the username was wrong\n\t\t_, _ = bcrypt.GenerateFromPassword([]byte(u.Username), 14)\n\t\treturn nil, ErrWrongUsernameOrPassword{}\n\t}\n\n\tif user.Issuer != IssuerLocal {\n\t\treturn user, &ErrAccountIsNotLocal{UserID: user.ID}\n\t}\n\n\t// The user is invalid if they need to verify their email address\n\tif user.Status == StatusEmailConfirmationRequired {\n\t\treturn &User{}, ErrEmailNotConfirmed{UserID: user.ID}\n\t}\n\n\t// Check the users password\n\terr = CheckUserPassword(user, u.Password)\n\tif err != nil {\n\t\tif IsErrWrongUsernameOrPassword(err) {\n\t\t\thandleFailedPassword(user)\n\t\t}\n\t\treturn user, err\n\t}\n\n\treturn user, nil\n}\n```\n\n### PoC\n1. Setup a Docker instance of Vikunja `v2.1.0` and create an account. Enable 2FA on the account.\n\"CleanShot\n\n2. Logout of the account.\n3. Using a web proxy, such as Burp Suite, craft an HTTP request to the endpoint similar to the one shown below. Ensure that the 2FA-enabled user's username and password is properly Base64-encoded and inserted into the `Authorization` header.\n\n```http\nPROPFIND /dav/principals/ HTTP/1.1\nHost: 127.0.0.1:3456\nAuthorization: Basic {{ REDACTED }}\n[ TRUNCATED ]\n\n\n```\n5. Observe that the response contains authenticated user information.\n```http\nHTTP/1.1 207 Multi-Status\nContent-Type: text/xml; charset=utf-8\nVary: Accept-Encoding\nDate: Mon, 16 Mar 2026 19:31:47 GMT\nContent-Length: 398\n\n/dav/projectsprojects\n[ TRUNCATED ]\n```\n6. Other requests can then be crafted to retrieve more information about a specific project, such as the one below.\n```http\nPROPFIND /dav/projects/1/{{ PROJECT NAME }}/ HTTP/1.1\nHost: 127.0.0.1:3456\nAuthorization: Basic [ REDACTED ]\n[TRUNCATED]\n\n\n```\n\n```http\nHTTP/1.1 207 Multi-Status\nContent-Type: text/xml; charset=utf-8\n[ TRUNCATED ]\n\n[ TRUNCATED ]\nBEGIN:VCALENDAR VERSION:2.0 X-PUBLISHED-TTL:PT4H X-WR-CALNAME:Inbox PRODID:-//Vikunja Todo App//EN BEGIN:VTODO UID:8gb6eclz-dad5-4a38-80a8-09005707eb51 DTSTAMP:20260316T190905Z SUMMARY:test DESCRIPTION:<p>description</p> CREATED:20260301T203712Z LAST-MODIFIED:20260316T190905Z BEGIN:VALARM TRIGGER;VALUE=DATE-TIME:20260316T130000Z ACTION:DISPLAY DESCRIPTION:test END:VALARM END:VTODO END:VCALENDARHTTP/1.1 200 OK\n[ TRUNCATED ]\n```\n\n### Impact\nAny user that has 2FA enabled could have it bypassed, allowing attacker access to a lot of the user's project information. \n\n### Remediation\nIf there are 2FA barriers to access an account in a specific fashion, all integrations should follow those if they're using the same methods of authentication. The easiest path is probably to disable Basic Authentication for Caldav by default, but keep the token access enabled, that way users can generate tokens specifically for Caldav if they want to use that feature. Basic Auth for it could be kept, but would most likely want to be a feature flag or something along those lines. That's so users can turn it on if it's necessary, but can be notified in the documentation that it's a more unsafe pattern if 2FA is enabled.", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-47cr-f226-r4pq.json?alt=media" }, { "category": "description", "text": "Vikunja has a 2FA Bypass via Caldav Basic Auth in code.vikunja.io/api", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGO-2026-4794.json?alt=media" }, { "category": "other", "text": "0.00084", "title": "EPSS" }, { "category": "other", "text": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N", "title": "CVSSV4" }, { "category": "other", "text": "6.9", "title": "CVSSV4 base score" }, { "category": "other", "text": "3.5", "title": "NCSC Score" }, { "category": "other", "text": "There is exploit data available from source Nvd, There is cwe data available from source Nvd, Is related to (a version of) an uncommon product, The value of the most recent EPSS score, Exploit code publicly available, The value of the most recent CVSS (V3) score", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5902485", "CSAFPID-5902768", "CSAFPID-5907212" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-47cr-f226-r4pq" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33315" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33315.json" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-47cr-f226-r4pq.json?alt=media" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGO-2026-4794.json?alt=media" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-47cr-f226-r4pq" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/go-vikunja/vikunja/commit/cdf5d30a425d032f749b78b98b828f25ad882615" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-47cr-f226-r4pq" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://vikunja.io/changelog/vikunja-v2.2.0-was-released" }, { "category": "external", "summary": "Reference - github; osv", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33315" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N", "baseScore": 4.3, "baseSeverity": "MEDIUM" }, "products": [ "CSAFPID-5902485", "CSAFPID-5902768", "CSAFPID-5907212" ] } ], "title": "CVE-2026-33315" } ] }