CVE-2026-25242 Overview
CVE-2026-25242 is a Missing Authorization vulnerability affecting Gogs, an open source self-hosted Git service. Versions 0.13.4 and below expose unauthenticated file upload endpoints by default, allowing remote attackers to upload arbitrary files to vulnerable servers without authentication.
Critical Impact
When the global RequireSigninView setting is disabled (default configuration), any remote user can upload arbitrary files to the server via /releases/attachments and /issues/attachments endpoints. This enables the instance to be abused as a public file host, potentially leading to disk exhaustion, unauthorized content hosting, or delivery of malware.
Affected Products
- Gogs versions 0.13.4 and below
- Gogs installations with default RequireSigninView setting (disabled)
- Self-hosted Gogs instances exposed to the network
Discovery Timeline
- 2026-02-19 - CVE-2026-25242 published to NVD
- 2026-02-19 - Last updated in NVD database
Technical Details for CVE-2026-25242
Vulnerability Analysis
This vulnerability stems from a Missing Authorization flaw (CWE-862) in Gogs' attachment upload functionality. The affected endpoints /issues/attachments and /releases/attachments were configured to use ignSignIn middleware instead of reqSignIn, allowing unauthenticated users to upload files when the RequireSigninView global setting is disabled.
The network-accessible attack vector with low complexity makes this vulnerability easily exploitable. CSRF tokens do not mitigate this attack because the browser issues same-origin cookies, allowing attackers to bypass CSRF protections when targeting these endpoints.
Root Cause
The root cause lies in improper access control configuration within the Gogs web routing setup. The file upload endpoints for issues and releases were grouped under middleware that only ignored sign-in requirements (ignSignIn) rather than requiring authentication (reqSignIn). This design flaw allowed any unauthenticated remote user to access these upload functionalities when the instance did not enforce sign-in for viewing content.
Attack Vector
An attacker can exploit this vulnerability remotely over the network without any authentication or user interaction. The attack involves sending HTTP POST requests directly to the vulnerable endpoints:
- Attacker identifies a Gogs instance with default configuration
- Attacker sends POST requests to /issues/attachments or /releases/attachments
- Arbitrary files are uploaded to the server without authentication
- Server storage can be exhausted or used to host malicious content
The following patch from GitHub Commit 628216d shows the security fix:
return
}
})
+ }, ignSignIn)
+
+ m.Group("", func() {
m.Post("/issues/attachments", repo.UploadIssueAttachment)
m.Post("/releases/attachments", repo.UploadReleaseAttachment)
- }, ignSignIn)
+ }, reqSignIn)
m.Group("/:username", func() {
m.Post("/action/:action", user.Action)
Source: GitHub Commit Update
The fix moves the attachment upload endpoints into a separate group that requires authentication (reqSignIn) rather than ignoring sign-in requirements (ignSignIn).
Detection Methods for CVE-2026-25242
Indicators of Compromise
- Unexpected files appearing in Gogs attachment storage directories
- Unusual HTTP POST requests to /issues/attachments or /releases/attachments from unauthenticated sessions
- Rapid disk space consumption on the Gogs server
- Web server logs showing high volume of attachment upload requests without corresponding authenticated sessions
Detection Strategies
- Monitor web server access logs for POST requests to /issues/attachments and /releases/attachments endpoints from unknown or unauthenticated sources
- Implement file integrity monitoring on Gogs attachment storage directories to detect unauthorized file uploads
- Deploy network intrusion detection rules to identify bulk upload attempts targeting vulnerable endpoints
- Review Gogs application logs for attachment upload events without corresponding user authentication
Monitoring Recommendations
- Set up alerts for abnormal disk usage growth on Gogs servers
- Configure web application firewall (WAF) rules to rate-limit requests to attachment upload endpoints
- Implement centralized logging for all Gogs instances to correlate potential abuse patterns
- Monitor for outbound traffic that may indicate the server is being used to distribute malicious content
How to Mitigate CVE-2026-25242
Immediate Actions Required
- Upgrade Gogs to version 0.14.1 or later immediately
- Enable the RequireSigninView setting as a temporary mitigation if immediate upgrade is not possible
- Audit existing attachment storage for unauthorized or suspicious files
- Review server logs for evidence of exploitation
Patch Information
This vulnerability has been fixed in Gogs version 0.14.1. The patch modifies the web routing configuration to require authentication for attachment upload endpoints. Organizations should upgrade to the patched version as soon as possible.
For detailed patch information, refer to:
Workarounds
- Enable RequireSigninView in the Gogs configuration to require authentication for all views, which prevents unauthenticated access to upload endpoints
- Implement network-level access controls to restrict access to Gogs instances from untrusted networks
- Deploy a reverse proxy or WAF to block unauthenticated POST requests to /issues/attachments and /releases/attachments
- Set disk quotas on the Gogs server to limit the impact of potential disk exhaustion attacks
# Configuration example - Enable RequireSigninView in app.ini
[security]
# Require users to sign in to view any page
REQUIRE_SIGNIN_VIEW = true
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
