Critical severity · published Jul 3, 2026
CVE-2026-26247
Gitea OAuth2 PKCE S256 challenges are not enforced during token exchange
9.1
CVSS
0.5%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 42% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
GO
Gitea Open Source Git Server · Gitea
before 1.25.5 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-26247
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-26247
blog.gitea.com
https://blog.gitea.com/release-of-1.25.5/
github.com
https://github.com/go-gitea/gitea/pull/36462
github.com
https://github.com/go-gitea/gitea/pull/36477
github.com
https://github.com/go-gitea/gitea/releases/tag/v1.25.5
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