Description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.5 before 19.0.6, 19.1 before 19.1.4, and 19.2 before 19.2.2 that under certain conditions could have allowed an unauthenticated user to cause a denial of service due to improper input validation.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.3",
  "pubDate": "2026-08-12T18:18:16.157Z",
  "pubdate": "2026-08-12T18:18:16.157Z",
  "executiveSummary": "A vulnerability related to improper input validation has been identified in GitLab CE/EE. This security flaw allows an unauthenticated remote attacker to induce a denial of service (DoS) state under specific operational conditions. The issue directly impacts service availability, potentially disrupting core application functionality and denying legitimate users access to the platform.\nThe vulnerability affects GitLab CE/EE across multiple version branches. Specifically, all versions starting from 18.5 prior to 19.0.6, versions in the 19.1 branch prior to 19.1.4, and versions in the 19.2 branch prior to 19.2.2 are vulnerable.\nExploitation of this vulnerability requires network access to the target GitLab instance, but does not necessitate user authentication or specialized privileges. The attack vector relies on supplying maliciously crafted inputs that trigger the improper validation routine, leading to resource exhaustion or application instability. Risk implications center on operational availability degradation, requiring immediate administrative intervention to patch the affected instances and restore normal service operations.",
  "technicalDetails": "The root cause of the vulnerability stems from improper input validation logic within the GitLab CE/EE application stack. When the application processes incoming requests containing specific untrusted input parameters under certain operational conditions, it fails to adequately sanitize, constrain, or validate the data structure before handling it.\nThe vulnerable component handles parsing and validation routines exposed to external network traffic. Because the endpoint is accessible to unauthenticated users, an attacker can directly interact with the vulnerable parsing mechanism without requiring prior session establishment or authorization credentials.\nThe attack flow proceeds as follows: First, the unauthenticated attacker crafts a malicious payload containing specially structured input designed to violate the implicit assumptions of the input processing routine. Second, the attacker transmits this payload over the network to the exposed GitLab service endpoint. Third, the application attempts to process the unvalidated input, triggering computational inefficiencies, excessive resource consumption, or unhandled exceptions within the affected component.\nThe payload behavior leverages the parsing weakness to exhaust server resources or crash the worker processes responsible for handling requests, resulting in a denial of service condition for the broader application. The post-exploitation impact is strictly confined to availability degradation, as unauthorized remote code execution or data exfiltration vectors are not present within the scope of this input validation failure.\nThe affected product is GitLab CE/EE. The vulnerable version ranges include all versions from 18.5 before 19.0.6, versions from 19.1 before 19.1.4, and versions from 19.2 before 19.2.2. Authentication and privilege requirements are entirely absent, as the attack can be executed by any unauthenticated network entity capable of reaching the vulnerable service interface."
}