CVE-2026-27771 Overview
CVE-2026-27771 is a missing authorization vulnerability [CWE-862] affecting Gitea versions up to and including 1.26.1. The flaw exists in the Composer package registry, where the application performs insufficient permission checks on package source links. Attackers can access source information for private or internal Composer packages without proper authorization. Gitea patched the issue in version 1.26.2.
Critical Impact
Unauthenticated remote attackers can retrieve source link information from private Composer packages hosted on affected Gitea instances, exposing internal repository data and potentially sensitive project metadata.
Affected Products
- Gitea versions up to and including 1.26.1
- Self-hosted Gitea instances exposing the Composer package registry
- Gitea deployments with private or internal Composer packages
Discovery Timeline
- 2026-07-03 - CVE-2026-27771 published to NVD
- 2026-07-07 - Last updated in NVD database
- Version 1.26.2 - Gitea releases security patch addressing the vulnerability
Technical Details for CVE-2026-27771
Vulnerability Analysis
The vulnerability resides in Gitea's Composer package registry endpoint handling. Composer is the dependency manager for PHP, and Gitea supports hosting Composer packages within its integrated package registry. When users publish Composer packages, Gitea generates source links pointing to the underlying Git repositories.
The affected code path fails to enforce repository visibility permissions when serving Composer package source links. Attackers query the Composer package endpoints and receive source references belonging to private or internal packages. The exposed data reveals repository paths, package metadata, and potentially version control references that should remain restricted to authorized users. The Exploit Prediction Scoring System (EPSS) places this issue in a high-probability tier for exploitation attempts.
Root Cause
The root cause is a missing authorization check [CWE-862] on Composer package source link resolution. Gitea's package handler returns source information based on package identifiers without validating whether the requesting user has read access to the underlying repository. Repository visibility flags (private, internal) are not consulted before returning source references.
Attack Vector
An unauthenticated attacker sends crafted requests to the Composer package registry endpoints on a target Gitea instance. Because the vulnerability requires no privileges and no user interaction, exploitation is straightforward over the network. Attackers can enumerate package identifiers and harvest source link information for repositories they should not be able to see. Refer to the GitHub Security Advisory GHSA-8qw8-rq86-9pc2 and the GitHub Pull Request Discussion for the underlying code changes.
Detection Methods for CVE-2026-27771
Indicators of Compromise
- Unusual volume of HTTP GET requests to /api/packages/*/composer/* endpoints on Gitea servers
- Requests to Composer package endpoints from unauthenticated sessions or unfamiliar source IP addresses
- Access log entries showing enumeration patterns across sequential package identifiers
Detection Strategies
- Review Gitea access logs for requests to Composer registry paths returning 200 OK responses without an associated authentication cookie or token
- Correlate anonymous Composer API requests with repositories flagged as private or internal in Gitea's database
- Alert on high-frequency Composer package metadata queries originating from a single client
Monitoring Recommendations
- Enable verbose HTTP access logging on the reverse proxy fronting Gitea and forward logs to a centralized SIEM
- Baseline normal Composer package request patterns and alert on statistical deviations
- Monitor Gitea audit logs for unexpected package registry activity outside business hours
How to Mitigate CVE-2026-27771
Immediate Actions Required
- Upgrade Gitea to version 1.26.2 or later as documented in the Gitea Release Announcement
- Audit private and internal Composer packages hosted on Gitea for signs of unauthorized enumeration in access logs
- Restrict network exposure of Gitea instances to trusted networks or authenticated users where feasible
Patch Information
Gitea released version 1.26.2 containing the authorization fix. Download the release from the Gitea Version 1.26.2 Release page. Administrators running container-based deployments should pull the updated image tag and redeploy.
Workarounds
- Disable the Composer package registry in Gitea configuration if the feature is not required by your organization
- Place Gitea behind an authenticating reverse proxy that blocks unauthenticated access to /api/packages/ endpoints
- Rotate any secrets or credentials that may have been referenced in exposed Composer package source metadata
# Configuration example: disable Composer package registry in app.ini
[packages]
ENABLED = true
[packages.composer]
ENABLED = false
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
