CVE-2026-5796: GitLab Package Registry Authorization Bypass (MEDIUM)

Technical summary

CVE-2026-5796 is an authorization bypass vulnerability in GitLab's group packages feature. The flaw exists in versions 13.6 through 18.11.6, 19.0 through 19.0.3, and 19.1 before 19.1.1. When group-level package permissions are checked, the system incorrectly allows Reporter-level users to enumerate or view package metadata from projects where the Package Registry is administratively disabled. This occurs because authorization checks in the group packages endpoint do not properly honor the project-level Package Registry disabled state. The vulnerability is rooted in improper access control (CWE-863) and requires valid GitLab credentials, limiting the attack surface to authenticated users already within the organization.

Business impact

Organizations using GitLab CE/EE may experience unintended information disclosure if they rely on disabling the Package Registry at the project level as a security boundary. Reporters or users with similar group-level access can inadvertently discover sensitive package metadata (names, versions, timestamps, etc.) from projects intended to have that feature disabled. This could expose information about internal dependencies, supply chain composition, or development practices to users with limited intended access. The impact is primarily confidentiality-focused, with no direct exposure to code or artifacts themselves, but may aid reconnaissance in multi-stage attacks.

Affected systems

The vulnerability affects GitLab CE and EE across a wide range of versions: all releases from 13.6 up to (but not including) 18.11.6, all 19.0.x releases before 19.0.3, and 19.1.x releases before 19.1.1. Organizations on 18.11.6, 19.0.3, 19.0.4+, 19.1.1, or later are not affected. Users of earlier major versions (13.5 and below) appear unaffected based on the published advisory scope.

Exploitability

Exploitation requires valid GitLab credentials and Reporter-level or higher group membership. No special user interaction is needed; an attacker with these privileges can directly query group package endpoints to view restricted metadata. The attack is straightforward API usage rather than complex exploitation, and the CVSS 3.1 score of 4.3 (MEDIUM) reflects the requirement for authentication and the limited scope of exposure. Public exploit code or weaponized tooling is not known to exist, and this is not on the KEV (Known Exploited Vulnerabilities) catalog.

Remediation

Upgrade GitLab CE/EE to patched versions: 18.11.6 or later, 19.0.3 or later, or 19.1.1 or later. Organizations unable to upgrade immediately should audit group membership and Reporter-level access, particularly for users or service accounts that should not view internal package metadata. Consider implementing additional network or API-level controls to restrict unauthenticated or out-of-policy group package queries. Verify that the Package Registry disabled setting at the project level is your organization's intended access control boundary and that no other compensating controls have been removed.

Patch guidance

GitLab has published patches across three supported release lines. Verify the patched versions from GitLab's official security advisory and release notes: 18.11.6+, 19.0.3+, and 19.1.1+ all contain the authorization fix. Schedule upgrades during your standard maintenance window; these are point releases and should not require extended preparation. Before upgrading, test in a non-production environment to confirm Package Registry access control behavior matches your security policy. After patching, verify that Reporter-level users no longer see package metadata from projects with the feature disabled.

Detection guidance

Monitor GitLab API audit logs for access to group packages endpoints (typically under `/api/v4/groups/{id}/packages`) from Reporter-level or lower-privileged accounts. Check for repeated queries listing package metadata from projects where the Package Registry is disabled. Review recently added or modified group membership for users with Reporter access to identify potential lateral movement by attackers. If available, use GitLab's built-in audit event filtering to flag unauthorized package metadata queries. Note that normal CI/CD pipelines may legitimately access packages; correlate suspicious queries with actual project work.

Why prioritize this

This vulnerability should be prioritized as MEDIUM based on CVSS score and organizational context. Rate it higher if your GitLab instance stores metadata for proprietary or sensitive packages, or if many service accounts or contractors hold Reporter-level group access. Rate it lower if Package Registry is rarely used or group access is tightly controlled to internal teams. The information disclosure risk is real but contained; no data exfiltration, code execution, or lateral escalation is possible through this flaw alone.

Risk score, explained

The CVSS 3.1 score of 4.3 reflects a low-complexity, network-accessible attack that requires authentication (PR:L) and compromises only the confidentiality of package metadata (C:L, I:N, A:N). The scope remains unchanged because the impact is limited to the user's own group permissions. The score is not elevated because exploitation does not require user interaction (UI:N) or high attack complexity (AC:L). Organizations with tighter access controls and limited use of the Package Registry feature will experience minimal real-world risk; those with broad Reporter-level access or sensitive package metadata should treat it as higher priority despite the numerical score.

Frequently asked questions