Server-Side Request Forgery (SSRF) in Gitea - CVE-2026-23603
Published: July 14, 2026
Vulnerability identifier: #VU137452
CSH Severity: Low
CVSS v4: 2.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-23603
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause the server to make arbitrary outbound HTTP requests.
The vulnerability exists due to server-side request forgery (ssrf) in OAuth2 avatar synchronization when fetching the OIDC picture claim URL. A remote user can supply a crafted avatar URL to cause the server to make arbitrary outbound HTTP requests.
Only instances with [oauth2_client] UPDATE_AVATAR = true enabled are vulnerable. The issue is blind by default, but limited response retrieval may be possible if a reachable internal endpoint returns a valid supported image within the configured avatar size limit.
Affected software
Gitea
How to mitigate CVE-2026-23603
Install security update from vendor's website.
Gitea - update to 1.27.0