# CVE-2026-58436: Gitea quadratic-time DoS in Locale middleware via Accept-Language header

Source: https://junglewise.ai/threats/cve-2026-58436-gitea-quadratic-time-dos-in-locale-middleware-via-accept-language  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-21. Updated: 2026-07-21  
License: CC BY 4.0 with a link back

CVE-2026-58436 · Severity: high · CVSS 4 · Published 2026-07-21

Gitea, a popular self-hosted Git service, is vulnerable to a denial-of-service attack that can be triggered by unauthenticated users. By sending a specially crafted web request with a malicious language header, an attacker can force the server to consume excessive CPU resources. This can lead to significant performance degradation or a complete service outage for all users.

Technologies: [Gitea](https://junglewise.ai/threats/technologies/gitea), [code.gitea.io/gitea (Go)](https://junglewise.ai/threats/technologies/code-gitea-io-gitea), [gitea.dev (Go)](https://junglewise.ai/threats/technologies/gitea-dev). Vendors: [Gitea](https://junglewise.ai/threats/vendors/gitea), [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-58436 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-58436 being exploited in the wild.

**How severe is CVE-2026-58436?** High severity, with a CVSS score of 4, published 21 July 2026.

**Which products and versions are affected?** Gitea < 1.27.0; code.gitea.io/gitea (Go) < 1.27.0, SEMVER:introduced=0,fixed=1.27.0; gitea.dev (Go) SEMVER:introduced=0,fixed=1.27.0.

**Is there a fix for CVE-2026-58436?** Yes. code.gitea.io/gitea (Go): upgrade to 1.27.0 or later; gitea.dev (Go): upgrade to 1.27.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-58436 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-58436?** Check whether you run Gitea, code.gitea.io/gitea (Go) or gitea.dev (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- code.gitea.io/gitea (Go): upgrade to 1.27.0 or later

  ```sh
  go get code.gitea.io/gitea@v1.27.0
  ```

- gitea.dev (Go): upgrade to 1.27.0 or later

  ```sh
  go get gitea.dev@v1.27.0
  ```


## Technical details

The Gitea Locale middleware calls golang.org/x/text/language.ParseAcceptLanguage on raw Accept-Language headers without prior validation. While the underlying Go library contains a guard against quadratic-time complexity (CVE-2022-32149) by limiting '-' characters, it fails to account for '_' characters which are aliased to '-' during parsing. An unauthenticated attacker can send a 1 MiB header containing many '_' separators to bypass the guard and trigger O(N²) behavior in the parser's scanner. This allows a small number of concurrent requests to saturate server CPU. The vulnerability is fixed in Gitea version 1.27.0 by implementing a limit on the number of separators allowed in the header.

## Affected products

- Gitea Gitea < 1.27.0

## Identifiers

- CVE-2026-58436
- GHSA-fw57-jgch-pgf3
- GO-2026-6055

## Timeline

- 2026-07-13: advisory: Initial GitHub Advisory published
- 2026-07-21: disclosed: Full advisory details released
- 2026-07-21: patched: Vulnerability addressed in version 1.27.0

## References

- [https://api.github.com/users/tonghuaroot](https://api.github.com/users/tonghuaroot)
- [https://github.com/tonghuaroot](https://github.com/tonghuaroot)
- [https://api.github.com/users/tonghuaroot/gists%7B/gist_id%7D](https://api.github.com/users/tonghuaroot/gists%7B/gist_id%7D)
- [https://api.github.com/users/tonghuaroot/repos](https://api.github.com/users/tonghuaroot/repos)
- [https://avatars.githubusercontent.com/u/23011166?v=4](https://avatars.githubusercontent.com/u/23011166?v=4)
- [https://api.github.com/users/tonghuaroot/events%7B/privacy%7D](https://api.github.com/users/tonghuaroot/events%7B/privacy%7D)

## Related threats

- [Gitea account takeover via OAuth2 auto-linking](https://junglewise.ai/threats/cve-2026-120263-when-oauth2-client-account-linking-is-set-to-auto-not-the)
- [Gitea limited-visibility profile disclosure via public-only token](https://junglewise.ai/threats/cve-2026-119627-the-web-profile-and-rss-atom-feed-routes-of-users-and)
- [Gitea token scope bypass in web routes](https://junglewise.ai/threats/cve-2026-119625-the-username-web-route-accepted-personal-access-tokens-over-http)
- [Gitea project boards information disclosure of private pull requests](https://junglewise.ai/threats/cve-2026-119533-repository-and-organization-project-boards-listed-the-pull)
- [Gitea API token scope bypass in repository deletion](https://junglewise.ai/threats/cve-2026-119441-delete-api-v1-orgs-org-repos-deletes-all-repositories-of-an)