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High, CVSS 7.5amended

nginx ignition has ParseAcceptLanguage _ separator bypass that enables ~75x CPU amplification via Accept-Language header in i18nMiddleware

CVE-2026-61629GHSA-jr34-h97m-9hpx

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/lucasdillmann/nginx-ignition 0.0.0-20260526022344-0c988fc1277c), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2026-61629: 0.42% estimated exploitation activity in the next 30 days; percentile 36.46 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary 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. Affected versions dillmann.com.br/nginx-ignition v2.40.0 and (per code inspection of main) earlier 2.x versions whose api/common/server/i18n.go middleware…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-jr34-h97m-9hpx

  2. Revision 2 · amended ·

    Amended from osv record GO-2026-6539

  3. Revision 1 · created ·

    Published from osv record GHSA-jr34-h97m-9hpx

Agent brief

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# Patch Next advisory brief: CVE-2026-61629

Advisory: nginx ignition has ParseAcceptLanguage `_` separator bypass that enables ~75x CPU amplification via Accept-Language header in i18nMiddleware
IDs: CVE-2026-61629, GHSA-jr34-h97m-9hpx
Record: https://patchnext.com/advisories/cve-2026-61629 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/lucasdillmann/nginx-ignition 0.0.0-20260526022344-0c988fc1277c. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/lucasdillmann/nginx-ignition: affected >= 0.0.0-20260126024607-cbaf0fc16ed8, < 0.0.0-20260526022344-0c988fc1277c; fixed in 0.0.0-20260526022344-0c988fc1277c

## Suggested inspection (read-only)
- Go github.com/lucasdillmann/nginx-ignition: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/lucasdillmann/nginx-ignition.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-jr34-h97m-9hpx (OSV record GHSA-jr34-h97m-9hpx lists affected ranges: Go github.com/lucasdillmann/nginx-ignition >=0.0.0-20260126024607-cbaf0fc16ed8 <0.0.0-20260526022344-0c988fc1277c (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6539 (OSV record GO-2026-6539 lists affected ranges: Go github.com/lucasdillmann/nginx-ignition >=0.0.0-20260126024607-cbaf0fc16ed8 <0.0.0-20260526022344-0c988fc1277c (fixed))
- Verified: https://github.com/advisories/GHSA-jr34-h97m-9hpx (GitHub-reviewed advisory GHSA-jr34-h97m-9hpx lists affected ranges: Go github.com/lucasdillmann/nginx-ignition >=0.0.0-20260126024607-cbaf0fc16ed8 <0.0.0-20260526022344-0c988fc1277c)

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