CVE-2026-1659: DoS in GitLab 9.0 - 18.11.3
Platform
gitlab
Component
gitlab
Fixed in
18.11.3
CVE-2026-1659 describes a denial-of-service vulnerability discovered in GitLab Community Edition (CE) and Enterprise Edition (EE). This flaw allows an unauthenticated attacker to disrupt GitLab services by sending specially crafted requests, leading to resource exhaustion. The vulnerability impacts versions ranging from 9.0.0 through 18.11.3, and a fix is available in version 18.11.3.
Impact and Attack Scenarios
Successful exploitation of CVE-2026-1659 can lead to a complete denial of service for GitLab instances. An attacker can overwhelm the server with malicious requests, preventing legitimate users from accessing the platform. This can disrupt critical development workflows, CI/CD pipelines, and collaboration efforts. The lack of authentication required for exploitation significantly broadens the attack surface, as any external user can potentially trigger the DoS. The impact is particularly severe for organizations heavily reliant on GitLab for their software development lifecycle.
Exploitation Context
CVE-2026-1659 was published on May 14, 2026. Severity is currently assessed as HIGH with a CVSS score of 7.5. No public proof-of-concept (POC) code has been released at the time of writing. There are no indications of active exploitation campaigns targeting this vulnerability. Monitor CISA advisories and GitLab security bulletins for updates.
Threat Intelligence
Exploit Status
CISA SSVC
CVSS Vector
What do these metrics mean?
- Attack Vector
- Network — remotely exploitable over the internet. No physical or local access required. Widest attack surface.
- Attack Complexity
- Low — no special conditions required. Attacker can exploit reliably without depending on rare configurations or timing.
- Privileges Required
- None — unauthenticated. No login or credentials needed to exploit.
- User Interaction
- None — attack is automatic and silent. Victim does nothing: no click, no file open.
- Scope
- Unchanged — impact is limited to the vulnerable component itself.
- Confidentiality
- None — no confidentiality impact. Attacker cannot read protected data.
- Integrity
- None — no integrity impact. Attacker cannot modify data.
- Availability
- High — complete crash or resource exhaustion. Full denial of service.
Affected Software
Weakness Classification (CWE)
Timeline
- Reserved
- Published
Mitigation and Workarounds
The primary mitigation for CVE-2026-1659 is to upgrade GitLab to version 18.11.3 or later. If an immediate upgrade is not feasible, consider implementing rate limiting on incoming requests to the GitLab instance to reduce the impact of potential attacks. Review GitLab's input validation mechanisms and consider implementing stricter controls to prevent malicious data from being processed. Monitor GitLab logs for unusual request patterns that may indicate exploitation attempts. After upgrading, confirm the fix by attempting to trigger the vulnerability with a crafted request; it should now be rejected.
How to fix
Actualice GitLab a la versión 18.9.7 o superior, 18.10.6 o superior, o 18.11.3 o superior para mitigar la vulnerabilidad. Esta actualización aborda la falta de validación de entrada que permitía a usuarios no autenticados causar una denegación de servicio.
Frequently asked questions
What is CVE-2026-1659 — DoS in GitLab 9.0 - 18.11.3?
CVE-2026-1659 is a denial-of-service vulnerability in GitLab CE/EE allowing unauthenticated users to cause service disruption via crafted requests due to insufficient input validation. It affects versions 9.0.0–18.11.3.
Am I affected by CVE-2026-1659 in GitLab 9.0 - 18.11.3?
If you are running GitLab CE or EE versions 9.0.0 through 18.11.3, you are potentially affected by this vulnerability. Check your GitLab version immediately.
How do I fix CVE-2026-1659 in GitLab 9.0 - 18.11.3?
Upgrade GitLab to version 18.11.3 or later to resolve this vulnerability. Consider rate limiting as a temporary mitigation if an immediate upgrade is not possible.
Is CVE-2026-1659 being actively exploited?
There are currently no indications of active exploitation campaigns targeting CVE-2026-1659, but it's crucial to apply the fix promptly.
Where can I find the official GitLab advisory for CVE-2026-1659?
Refer to the official GitLab security advisory for detailed information and updates: [https://gitlab.com/security/security advisories](https://gitlab.com/security/security advisories)
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