TI-2026-21232 Aliases CVE-2026-26247 GHSA-m5ch-ppfx-xv3v

Gitea OAuth2 PKCE S256 challenges are not enforced during token exchange

MEDIUM 48CWE-284Published 2026-07-03 · Updated 2026-07-07

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Security bypass
Confidentiality · integrity · availability: High · High · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and GitHub. Impact type from CWE-284.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00495 42nd percentileScored 2026-11-07

Fix Fixed Gitea Open Source Git Server (Gitea): 1.25.5code.gitea.io/gitea (Go): 1.25.5

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Gitea	Gitea Open Source Git Server	before 1.25.5	1.25.5	Patch available	CNA
—	code.gitea.io/gitea (Go)	before 1.25.5	1.25.5	Patch available	GHSA-m5ch-ppfx-xv3v

Gitea Open Source Git Server VendorGitea Affected before 1.25.5 Fixed in 1.25.5 Patch available CNA
code.gitea.io/gitea (Go) Vendor— Affected before 1.25.5 Fixed in 1.25.5 Patch available GHSA-m5ch-ppfx-xv3v

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:gitea:gitea::::::::	—	—	Gitea

cpe:2.3:a:gitea:gitea:*:*:*:*:*:*:*:* Versions — — ·Gitea

Remediation

Fix · CNA Gitea Open Source Git Server (Gitea) Fixed in 1.25.5
Fix · GHSA-m5ch-ppfx-xv3v code.gitea.io/gitea (Go) Fixed in 1.25.5 Advisory →

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-07-03
Gitea Open Source Git Server 1.25.5
14 records Highest priority Priority MEDIUM 7 MEDIUM, 7 LOW
Other records, highest priority first
- TI-2026-21259 Gitea LFS mirror synchronization bypasses migration HTTP transport restrictionsPriority MEDIUM 50
- TI-2026-21222 Gitea OAuth2 authorization codes lack expiry and reuse enforcementPriority MEDIUM 48
- TI-2026-20788 Gitea template repository generation mishandles symlinked pathsPriority MEDIUM 48
Show all 14 records →

Timeline

2026-10-02 Threatist record created from CVE-2026-26247
2026-10-03 Alias added: GHSA-m5ch-ppfx-xv3v

References

Patch 2

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-26247

Other 6

TI-2026-42785 Gitea before 1.27.1 allows remote code execution via the diffpatch API through Git hook installation. KEVCVSS 3.1CRITICAL 9.8
TI-2026-42033 Improper authorization on OAuth sign-in callback silently re-enables administrator-disabled accounts CVSS 3.1CRITICAL 9.8
TI-2026-40842 Privilege Escalation via Access Token Scope Escalation in API CVSS 3.1CRITICAL 9.8
TI-2026-16922 Gitea Docker image trusts spoofable reverse-proxy headers by default CVSS 3.1CRITICAL 9.8
TI-2026-42043 Team-repository linking endpoint bypasses the RepoAdminChangeTeamAccess organization setting CVSS 3.1CRITICAL 9.1
TI-2026-40381 OIDC userinfo Endpoint Returns Identity Claims Without Enforcing API Token Scopes CVSS 3.1CRITICAL 9.1

See all 240 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences