VulnerabilityDeferred

CVE-2026-26247

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.

CRITICAL 9.1EPSS 0.50%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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.

CVSS 3.1: 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS: 0.50% probability · 41th percentile
CISA KEV: Not listed
Weakness: CWE-284
Source: 88ee5874-cf24-4952-aea0-31affedb7ff2

References

https://blog.gitea.com/release-of-1.25.5/
https://github.com/go-gitea/gitea/pull/36462
https://github.com/go-gitea/gitea/pull/36477
https://github.com/go-gitea/gitea/releases/tag/v1.25.5

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.