Answer in brief
CVE-2026-61629 records a High severity (CVSS 7.5) vulnerability in nginx ignition has ParseAcceptLanguage `_` separator bypass that enables ~75x CPU amplification via Accept-Language header in i18nMiddleware. The current sources do not mark it as known exploited. The current feed maps lucasdillmann/nginx-ignition (generic), github.com/lucasdillmann/nginx-ignition (go), github.com/lucasdillmann/nginx-ignition (go). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps lucasdillmann/nginx-ignition (generic), github.com/lucasdillmann/nginx-ignition (go), github.com/lucasdillmann/nginx-ignition (go). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| lucasdillmann/nginx-ignitiongeneric | >=2.29.0 <2.40.1 | 2.40.1 |
| github.com/lucasdillmann/nginx-ignitiongo | >=0.0.0-20260126024607-cbaf0fc16ed8,<0.0.0-20260526022344-0c988fc1277c | 0.0.0-20260526022344-0c988fc1277c |
| github.com/lucasdillmann/nginx-ignitiongo | >=0.0.0-20260126024607-cbaf0fc16ed8 <0.0.0-20260526022344-0c988fc1277c | 0.0.0-20260526022344-0c988fc1277c |
Published upstream
Sep 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 21, 2026
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.
Quoted source text, attributed separately from HOL analysis.