{"id":"CVE-2026-61629","published":"2026-09-21T15:17:30.477","lastModified":"2026-09-21T15:17:30.477","description":"nginx ignition is a user interface for the nginx web server. In versions 2.29.0 through 2.40.0, the gin i18n middleware in nginx-ignition's API server runs in front of every HTTP request and calls `golang.org/x/text/language.ParseAcceptLanguage` on the raw `Accept-Language` header without imposing any size or shape filter. The underlying parser has quadratic-time behaviour on long lists of malformed language tags. The CVE-2022-32149 guard that golang.org/x/text added in v0.3.8 caps the number of `-` characters in the input at 1000, but it does not cap `_` characters even though the parser's internal scanner aliases `_` to `-` before parsing. A single unauthenticated GET request with an `Accept-Language` header built out of `_` separators burns about 2.4 seconds of server CPU on the host running nginx-ignition; ten concurrent attackers saturate a ten-core box for the duration of the attack while consuming ~10 MiB/s of upstream bandwidth. Version 2.40.1 fixes this issue.","cvssScore":7.5,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwes":["CWE-770"],"vendors":[],"products":[],"references":[{"url":"https://github.com/lucasdillmann/nginx-ignition/commit/0c988fc1277c7d291725e8373313f8486fa1b31a","tags":[]},{"url":"https://github.com/lucasdillmann/nginx-ignition/commit/cbaf0fc16ed873f7178a2ca9b0d00a696e44b485","tags":[]},{"url":"https://github.com/lucasdillmann/nginx-ignition/security/advisories/GHSA-jr34-h97m-9hpx","tags":[]}],"exploitRefs":[{"url":"https://github.com/lucasdillmann/nginx-ignition/commit/0c988fc1277c7d291725e8373313f8486fa1b31a","tags":[]},{"url":"https://github.com/lucasdillmann/nginx-ignition/commit/cbaf0fc16ed873f7178a2ca9b0d00a696e44b485","tags":[]},{"url":"https://github.com/lucasdillmann/nginx-ignition/security/advisories/GHSA-jr34-h97m-9hpx","tags":[]}],"hasPoc":true,"ai":{"summary":"The flaw allows unauthenticated attackers to perform a denial of service (DoS) by sending specially crafted requests that consume excessive CPU resources.","exploitability":"Exploitation is relatively easy as it requires sending specific `Accept-Language` headers, and can be performed concurrently by multiple attackers.","blast_radius":"If exploited, the attack could significantly impact server performance, potentially affecting availability for legitimate users.","remediation":"Update to nginx-ignition version 2.40.1 or later to mitigate this vulnerability.","tags":["dos","web","nginx","i18n"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-09-22T06:12:16.223Z"}}