CVE-2021-22245 in Community Edition
Summary
by MITRE • 08/25/2021
Improper validation of commit author in GitLab CE/EE affecting all versions allowed an attacker to make several pages in a project impossible to view
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Analysis
by VulDB Data Team • 08/29/2021
The vulnerability identified as CVE-2021-22245 represents a critical security flaw in GitLab Community Edition and Enterprise Edition versions that allows attackers to manipulate commit author validation mechanisms. This issue stems from insufficient input sanitization and validation of commit author information within the GitLab platform, creating a pathway for malicious actors to exploit the system's commit handling functionality. The vulnerability specifically targets the commit author field in Git operations, where the system fails to properly validate the authenticity and format of author information associated with commits.
The technical implementation of this vulnerability occurs at the GitLab core processing layer where commit author data is parsed and validated. When an attacker crafts a malicious commit with specially formatted author information, the system's validation logic fails to properly sanitize or reject the malformed input. This improper validation allows the attacker to inject content that disrupts the normal rendering and display mechanisms of GitLab's web interface. The flaw manifests when the system attempts to process and display commit information, particularly affecting how author details are rendered in project pages, commit histories, and related user interface components.
The operational impact of CVE-2021-22245 extends beyond simple data corruption or display issues, as it fundamentally compromises the integrity of project pages within GitLab repositories. When exploited, this vulnerability can render multiple pages within a project inaccessible or completely broken, effectively creating a denial-of-service condition for legitimate users attempting to access commit information. The attack surface is particularly concerning because it affects all versions of GitLab CE/EE, meaning organizations with older installations are equally vulnerable. This vulnerability can be exploited to cause widespread disruption across projects, potentially affecting development workflows, code review processes, and collaborative development environments that depend on GitLab's commit visualization features.
This vulnerability aligns with CWE-20, which describes "Improper Input Validation," and can be mapped to ATT&CK technique T1059.001 for command and scripting interpreter usage, as attackers may leverage this flaw to manipulate system behavior through crafted commit data. The attack vector typically involves creating a malicious commit with specially crafted author information that bypasses validation checks, then pushing this commit to a target repository. The exploitation process may also involve social engineering elements where attackers convince users to view compromised project pages, or automated scanning tools that identify vulnerable installations. Organizations should implement immediate mitigations including updating to patched versions of GitLab, implementing additional input validation controls, and monitoring for suspicious commit patterns within their repositories.
The remediation approach for CVE-2021-22245 requires organizations to upgrade their GitLab installations to versions that contain the proper validation fixes. This upgrade process should include thorough testing of the patched environment to ensure that existing functionality remains intact while addressing the specific validation issues. System administrators should also consider implementing additional monitoring and alerting mechanisms to detect potential exploitation attempts, particularly around commit author information and repository access patterns. Security teams should conduct comprehensive vulnerability assessments to identify any other systems that might be affected by similar validation flaws in source code management systems or version control platforms. The vulnerability demonstrates the critical importance of proper input validation in web applications and source code management systems, where seemingly innocuous data fields can become attack vectors when not properly sanitized and validated.