Account linking without session binding in Gitea OpenID
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Security bypass, Tampering
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-287 and CWE-352.
Summary
Gitea through 28.1.0 accepts an OpenID 2.0 assertion in the security settings association callback without checking that the signed-in user started the linking. This is an improper authentication flaw (CWE-287) that lets an attacker-controlled OpenID provider attach its identity to a victim's account. An unauthenticated remote attacker needs the victim to open a crafted link, and the attacker can then sign in as the victim through OpenID login, which skips the local TOTP and WebAuthn checks.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
Description from the CNA
The Gitea OpenID association callback in the security settings accepted a positive OpenID 2.0 assertion without checking that the signed-in user had started the linking. Because OpenID 2.0 allows unsolicited assertions, an attacker-controlled OpenID provider could attach the attacker's identity to the account of a signed-in victim who opened a crafted link, and the attacker could then sign in as the victim through OpenID login, which does not apply the local TOTP or WebAuthn checks. The callback now requires a time-limited `state` value bound to the user.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
The sources list no fixed version for Gitea.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
Timeline
- 2026-10-18 Threatist record created from CVE-2026-104627
- 2026-10-20 CVSS score added · CISA ADP
- 2026-10-20 CISA SSVC decision points changed
References
More Gitea vulnerabilities
- 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
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences