Gitea OAuth2 PKCE S256 verifier bypass

CRITICAL 9.1CVE-2026-26247 · GHSA-m5ch-ppfx-xv3v · GO-2026-6342 · Published 03/07/2026 · updated 25/10/2026

Package	Affected versions	Patched versions
code.gitea.io/gitea Go	`< 1.25.5`	`1.25.5`

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.

NVD 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.

References

nvd.nist.gov/vuln/detail/CVE-2026-26247 · ADVISORY
go-gitea/gitea#36462 · WEB
go-gitea/gitea#36477 · WEB
go-gitea/gitea commit 750649c · WEB
go-gitea/gitea commit bf8d11b · WEB
blog.gitea.com/release-of-1.25.5 · WEB
go-gitea/gitea · PACKAGE
go-gitea/gitea release v1.25.5 · WEB
blog.gitea.com/release-of-1.25.5
GitHub Advisory GHSA-m5ch-ppfx-xv3v · ADVISORY

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