{ "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-2026-34715", "tracking": { "current_release_date": "2026-04-03T16:39:43.081755Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-34715", "initial_release_date": "2026-04-01T23:02:32.231383Z", "revision_history": [ { "date": "2026-04-01T23:02:32.231383Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-04-01T23:02:37.786854Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-04-02T18:27:26.603383Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)." }, { "date": "2026-04-02T18:27:28.534508Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-04-02T18:47:45.161050Z", "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": "2026-04-02T18:47:47.234598Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-04-03T15:31:08.925695Z", "number": "7", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-04-03T15:31:10.568195Z", "number": "8", "summary": "NCSC Score updated." }, { "date": "2026-04-03T16:38:46.692087Z", "number": "9", "summary": "Unknown change." } ], "status": "interim", "version": "9" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<3.0.6", "product": { "name": "vers:unknown/<3.0.6", "product_id": "CSAFPID-5985189" } } ], "category": "product_name", "name": "ewe" } ], "category": "vendor", "name": "vshakitskiy" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-34715", "cwe": { "id": "CWE-113", "name": "Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')" }, "notes": [ { "category": "description", "text": "### Summary\n\nThe `encode_headers` function in `src/ewe/internal/encoder.gleam` directly interpolates response header keys and values into raw HTTP bytes without validating or stripping CRLF (`\\r\\n`) sequences. An application that passes user-controlled data into response headers (e.g., setting a `Location` redirect header from a request parameter) allows an attacker to inject arbitrary HTTP response content, leading to response splitting, cache poisoning, and possible cross-site scripting.\n\nNotably, ewe *does* validate CRLF in **incoming** request headers via `validate_field_value()` in the HTTP/1.1 parser — but provides no equivalent protection for **outgoing** response headers in the encoder.\n\n### Details\n\n**File:** `src/ewe/internal/encoder.gleam`\n\n**Vulnerable code:**\n```gleam\nfn encode_headers(headers: List(#(String, String))) -> BitArray {\n let headers =\n list.fold(headers, <<>>, fn(acc, headers) {\n let #(key, value) = headers\n <>\n })\n\n <>\n}\n```\n\nBoth `key` and `value` are embedded directly into the `BitArray` output. If either contains `\\r\\n`, the resulting bytes become a structurally valid but attacker-controlled HTTP response, terminating the current header early and injecting new headers or a second HTTP response.\n\n**Contrast with request parsing** (`src/ewe/internal/http1.gleam`): incoming header values are protected:\n```gleam\nuse value <- try(\n validate_field_value(value) |> replace_error(InvalidHeaders)\n)\n```\n\nNo analogous validation exists for outgoing header values in the encoder. The solution is to strip or reject `\\r` (0x0D) and `\\n` (0x0A) from all header key and value strings in `encode_headers` before encoding, mirroring the validation already applied to incoming request headers via `validate_field_value()`\n\n### PoC\n\nAn ewe application echoes a user-supplied redirect URL into a `Location` header:\n\n```gleam\nfn handle_request(req: Request) -> Response {\n let redirect_url =\n request.get_query(req)\n |> result.try(list.key_find(_, \"next\"))\n |> result.unwrap(\"/home\")\n\n response.new(302)\n |> response.set_header(\"location\", redirect_url)\n |> response.set_body(ewe.Empty)\n}\n```\n\nAttacker request:\n```bash\nprintf 'GET /?next=https://example.com%%0d%%0aX-Injected:%%20true HTTP/1.1\\r\\nHost: localhost\\r\\n\\r\\n' | nc -w 2 localhost 8080\n```\n\nResulting response:\n```\nHTTP/1.1 302 Found\nlocation: https://example.com\nX-Injected: true\ncontent-length: 0\ndate: Tue, 24 Mar 2026 07:53:00 GMT\nconnection: keep-alive\n\n\n```\n\nThe `X-Injected: true` header appears as a separate response header, confirming that CRLF sequences in user input are not sanitized by the encoder.", "title": "github - https://api.github.com/advisories/GHSA-x2w3-23jr-hrpf" }, { "category": "description", "text": "ewe is a Gleam web server. Prior to version 3.0.6, the encode_headers function in src/ewe/internal/encoder.gleam directly interpolates response header keys and values into raw HTTP bytes without validating or stripping CRLF (\\r\\n) sequences. An application that passes user-controlled data into response headers (e.g., setting a Location redirect header from a request parameter) allows an attacker to inject arbitrary HTTP response content, leading to response splitting, cache poisoning, and possible cross-site scripting. Notably, ewe does validate CRLF in incoming request headers via validate_field_value() in the HTTP/1.1 parser — but provides no equivalent protection for outgoing response headers in the encoder. This issue has been patched in version 3.0.6.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-34715" }, { "category": "description", "text": "ewe is a Gleam web server. Prior to version 3.0.6, the encode_headers function in src/ewe/internal/encoder.gleam directly interpolates response header keys and values into raw HTTP bytes without validating or stripping CRLF (\\r\\n) sequences. An application that passes user-controlled data into response headers (e.g., setting a Location redirect header from a request parameter) allows an attacker to inject arbitrary HTTP response content, leading to response splitting, cache poisoning, and possible cross-site scripting. Notably, ewe does validate CRLF in incoming request headers via validate_field_value() in the HTTP/1.1 parser — but provides no equivalent protection for outgoing response headers in the encoder. This issue has been patched in version 3.0.6.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/34xxx/CVE-2026-34715.json" }, { "category": "other", "text": "0.00029", "title": "EPSS" }, { "category": "other", "text": "3.9", "title": "NCSC Score" }, { "category": "other", "text": "The value of the most recent EPSS score, There is cwe data available from source Nvd", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5985189" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-x2w3-23jr-hrpf" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-34715" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/34xxx/CVE-2026-34715.json" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/vshakitskiy/ewe/security/advisories/GHSA-x2w3-23jr-hrpf" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-x2w3-23jr-hrpf" }, { "category": "external", "summary": "Reference - cveprojectv5; nvd", "url": "https://github.com/vshakitskiy/ewe/commit/ce4ff214d32626a10fda9398dc94a2d720e17446" }, { "category": "external", "summary": "Reference - cveprojectv5; nvd", "url": "https://github.com/vshakitskiy/ewe/releases/tag/v3.0.6" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N", "baseScore": 5.3, "baseSeverity": "MEDIUM" }, "products": [ "CSAFPID-5985189" ] } ], "title": "CVE-2026-34715" } ] }