CVE intelligence and bounded remediation

CVE-2021-39889 — Gitlab Gitlab security vulnerability

Medium CVSS 4.3

In all versions of GitLab EE since version 14.1, due to an insecure direct object reference vulnerability, an endpoint may reveal the protected branch name to a malicious user who makes a crafted API call with the ID of the protected branch.

Severity
Medium
CVSS
4.3 (3.1)
Published
2021-10-05
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-639

Affected products

  • gitlab / gitlab

Showing 1 representative product identities from 3 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

The detailed catalog view below loads this exact record, its source evidence, and the full seven-phase agentic change plan.