CVE-2026-26247
Gitea OAuth2 PKCE S256 challenges are not enforced during token exchange
CRITICAL 9.1
At a glance
- Source
- NVD
- EPSS
- EPSS 0.50 % · percentile 42 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- Gitea
- NVD status
- Deferred
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.
Weaknesses (CWE)
- CWE-284 — Improper Access Control
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | CRITICAL 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | CISA-ADP |
| CVSS 3.1 | CRITICAL 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | NVD · 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary) |
Advisories
- GHSA-m5ch-ppfx-xv3v — Gitea OAuth2 PKCE S256 verifier bypass
- GO-2026-6342 — Gitea OAuth2 PKCE S256 verifier bypass in code.gitea.io/gitea
European references
- ENISA EUVD · EUVD-2026-41629
- GCVE · GCVE-0-2026-26247
Affected products
| Product | Versions |
|---|---|
| Gitea · Gitea Open Source Git Server | affected 0 < 1.25.5 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |