Gitea: ParseAcceptLanguage quadratic-time DoS via Locale middleware on unauthenticated requests

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-58436: 0.61% estimated exploitation activity in the next 30 days; percentile 49.23 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The Locale middleware that runs in front of every unauthenticated request calls golang.org/x/text/language.ParseAcceptLanguage on the raw Accept-Language header without imposing a 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 ~2 seconds of server CPU on the host running Gitea; ten concurrent attackers saturate a ten-core box for the duration of the attack while consuming ~1 MiB of upstream bandwidth per request. Affected versions code.gitea.io/gitea 1.22.6 and (per code inspection of main) all earlier and later 1.22.x / 1.23.x / 1.24.x / 1.25.x / 1.26.x versions that do not impose their own size…

Published by the source

21 Jul 2026, 21:15 UTC

Last modified by the source

21 Jul 2026, 21:15 UTC

Source last checked

26 Oct 2026, 15:27 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fw57-jgch-pgf3

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-58436

Advisory: Gitea: ParseAcceptLanguage quadratic-time DoS via Locale middleware on unauthenticated requests
IDs: CVE-2026-58436, GHSA-fw57-jgch-pgf3
Record: https://patchnext.com/advisories/cve-2026-58436 (revision 1, source checked 26 Oct 2026, 15:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: code.gitea.io/gitea 1.27.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go code.gitea.io/gitea: affected < 1.27.0; fixed in 1.27.0

## Suggested inspection (read-only)
- Go code.gitea.io/gitea: 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 code.gitea.io/gitea.
- 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://github.com/advisories/GHSA-fw57-jgch-pgf3 (GitHub-reviewed advisory GHSA-fw57-jgch-pgf3 lists affected ranges: Go code.gitea.io/gitea >=0 <1.27.0)

Commands are suggestions: review each one before running it.