An XSS flaw in GitLab allows attackers to take over accounts

GitLab Community and Enterprise Editions contain a critical improper access control flaw (CWE-640) in which password reset emails for a user account could be delivered to an unverified email address. Because the password reset flow is reachable over the network without authentication or user interaction (CVSS 3.1: AV:N/AC:L/PR:N/UI:N), an unauthenticated remote attacker could trigger a password reset for a victim's account such that the reset link lands on an attacker-controlled, unverified email address, then set a new password and hijack the account. Taking over an account gives the attacker that account's privileges, so compromise of an administrator account could expose the instance's code repositories, settings, and any secrets or CI/CD credentials they can reach. All GitLab CE/EE versions from 16.1 through 16.7 prior to the patched releases (16.1.6, 16.2.9, 16.3.7, 16.4.5, 16.5.6, 16.6.4, and 16.7.2) are affected. The flaw is under active exploitation: it carries an EPSS of 94.6% (100th percentile), was added to CISA's Known Exploited Vulnerabilities catalog on 2024-05-01, and news coverage confirms attackers are hijacking accounts in the wild.

Do: Upgrade affected GitLab CE/EE instances immediately to the patched release for your track — 16.1.6, 16.2.9, 16.3.7, 16.4.5, 16.5.6, 16.6.4, or 16.7.2 (or later) — prioritizing internet-facing instances given active exploitation and the KEV listing. Audit user accounts for unverified or unexpected email addresses and review logs for password reset activity to identify possible takeovers, and rotate credentials for any high-privilege accounts you suspect were compromised.

A XSS condition exists within GitLab in versions 15.11 before 16.10.6, 16.11 before 16.11.3, and 17.0 before 17.0.1. By leveraging this condition, an attacker can craft a malicious page to exfiltrate sensitive user information.