GHSA-m5ch-ppfx-xv3v

Gitea OAuth2 PKCE S256 verifier bypass

At a glance

Published: 2026-07-03 21:31 UTC
Updated: 2026-09-02 19:41 UTC
CVE: CVE-2026-26247
Aliases: GO-2026-6342
CVSS_V3: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Description

Gitea versions before 1.25.5 do not persist the OAuth2 PKCE S256 challenge method correctly during authorization, allowing token exchange without the expected verifier check.

Affected packages

Package	Versions
Go · code.gitea.io/gitea	introduced 0, fixed 1.25.5

References

https://nvd.nist.gov/vuln/detail/CVE-2026-26247 ADVISORY
https://github.com/go-gitea/gitea/pull/36462 WEB
https://github.com/go-gitea/gitea/pull/36477 WEB
https://github.com/go-gitea/gitea/commit/750649c1ef092c95f95b206b9d5fa17471a0b1f5 WEB
https://github.com/go-gitea/gitea/commit/bf8d11bb212ba2a76596d8a90e74e7d664571324 WEB
https://blog.gitea.com/release-of-1.25.5 WEB
https://github.com/go-gitea/gitea PACKAGE
https://github.com/go-gitea/gitea/releases/tag/v1.25.5 WEB

Sources

Source	Licence
OSV.dev	CC-BY 4.0 — GitHub Advisory Database