{"cve":"CVE-2026-61629","nvd":{"published":"2026-09-21T15:17:30.477","modified":"2026-09-24T23:17:13.280","status":"Awaiting Analysis","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-770"],"references":["https://github.com/lucasdillmann/nginx-ignition/commit/0c988fc1277c7d291725e8373313f8486fa1b31a","https://github.com/lucasdillmann/nginx-ignition/commit/cbaf0fc16ed873f7178a2ca9b0d00a696e44b485","https://github.com/lucasdillmann/nginx-ignition/security/advisories/GHSA-jr34-h97m-9hpx","https://github.com/lucasdillmann/nginx-ignition/security/advisories/GHSA-jr34-h97m-9hpx"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-61629","score":0.00421,"percentile":0.36435,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-jr34-h97m-9hpx","url":"https://osv.dev/vulnerability/GHSA-jr34-h97m-9hpx","summary":"nginx ignition has  ParseAcceptLanguage `_` separator bypass that enables ~75x CPU amplification via Accept-Language header in i18nMiddleware","modified":"2026-09-28T17:11:07.357176648Z","packages":[{"ecosystem":"Go","name":"github.com/lucasdillmann/nginx-ignition","purl":"pkg:golang/github.com/lucasdillmann/nginx-ignition","ranges":[">=0.0.0-20260126024607-cbaf0fc16ed8 <0.0.0-20260526022344-0c988fc1277c"],"fixed":["0.0.0-20260526022344-0c988fc1277c"]}]},{"id":"GO-2026-6539","url":"https://osv.dev/vulnerability/GO-2026-6539","summary":"nginx ignition has ParseAcceptLanguage `_` separator bypass that enables ~75x CPU amplification via Accept-Language header in i18nMiddleware in github.com/lucasdillmann/nginx-ignition","modified":"2026-09-28T17:00:25.959306615Z","packages":[{"ecosystem":"Go","name":"github.com/lucasdillmann/nginx-ignition","purl":"pkg:golang/github.com/lucasdillmann/nginx-ignition","ranges":[">=0.0.0-20260126024607-cbaf0fc16ed8 <0.0.0-20260526022344-0c988fc1277c"],"fixed":["0.0.0-20260526022344-0c988fc1277c"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}