What is GHSA-m5ch-ppfx-xv3v?

GHSA-m5ch-ppfx-xv3v is a security advisory published by GitHub Security Advisories with Critical severity. Gitea OAuth2 PKCE S256 verifier bypass

Which CVE IDs does GHSA-m5ch-ppfx-xv3v cover?

GHSA-m5ch-ppfx-xv3v covers the following CVE IDs: CVE-2026-26247. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of GHSA-m5ch-ppfx-xv3v?

GHSA-m5ch-ppfx-xv3v has a CVSS v3 base score of 9.1, published by GitHub Security Advisories.

Which products are affected by GHSA-m5ch-ppfx-xv3v?

GHSA-m5ch-ppfx-xv3v affects 1 product, including: go/code.gitea.io/gitea:\u003c 1.25.5.

GHSA-m5ch-ppfx-xv3vCriticalCVSS 9.1

Gitea OAuth2 PKCE S256 verifier bypass

Vendor

GitHub Security Advisories

Published

July 3, 2026

Last Modified

September 1, 2026

🔗 CVE IDs covered (1)

CVE-2026-26247 →

📋 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 products1

go/code.gitea.io/gitea:< 1.25.5

🔗 References (8)

https://nvd.nist.gov/vuln/detail/CVE-2026-26247
https://github.com/go-gitea/gitea/pull/36462
https://github.com/go-gitea/gitea/pull/36477
https://blog.gitea.com/release-of-1.25.5
https://github.com/go-gitea/gitea/releases/tag/v1.25.5
https://github.com/go-gitea/gitea/commit/750649c1ef092c95f95b206b9d5fa17471a0b1f5
https://github.com/go-gitea/gitea/commit/bf8d11bb212ba2a76596d8a90e74e7d664571324
https://github.com/advisories/GHSA-m5ch-ppfx-xv3v