Introduction
Account compromise and unauthorized repository changes are real risks when a cross-site scripting flaw impacts a core developer workflow. CVE-2025-7734, a high-severity vulnerability in GitLab's blob viewer, demonstrates how a single input validation oversight can expose entire development teams to attack.
GitLab is a leading DevOps platform used by millions of organizations for source code management, CI/CD, and collaborative development. Its Community and Enterprise Editions are widely deployed across industries, making vulnerabilities in its core components especially impactful.
Technical Information
CVE-2025-7734 is a cross-site scripting (XSS) vulnerability (CWE-79) in the blob viewer component of GitLab CE/EE. The blob viewer is responsible for rendering repository file contents in the web interface, supporting syntax highlighting, line numbers, and other review features.
The vulnerability arises from insufficient input validation and output encoding when displaying file content or metadata. Specifically, attackers with the ability to commit files to a repository could inject malicious JavaScript payloads into file contents, filenames, or associated metadata. When another authenticated user viewed the affected file in the blob viewer, the injected script would execute in the context of their browser session. This could allow the attacker to perform actions on behalf of the victim, such as modifying repositories, accessing confidential data, or escalating privileges.
The flaw affects all versions of GitLab CE/EE from 14.2 before 18.0.6, 18.1 before 18.1.4, and 18.2 before 18.2.2. The root cause is improper sanitization and encoding in the blob viewer's rendering logic. No public code snippets or PoC are available for this issue.
Patch Information
In the latest GitLab patch release (versions 18.2.2, 18.1.4, and 18.0.6), several critical security vulnerabilities have been addressed to enhance the platform's security posture.
Cross-Site Scripting (XSS) Vulnerabilities:
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Blob Viewer XSS (CVE-2025-7734): An issue was identified where attackers could inject malicious content into the blob viewer, potentially executing actions on behalf of users. The patch introduces stringent input validation and output encoding mechanisms to neutralize such threats.
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Labels XSS (CVE-2025-7739): Authenticated users could exploit this vulnerability by embedding malicious HTML in scoped label descriptions. The update ensures that all label descriptions are properly sanitized before rendering, preventing the execution of unauthorized scripts.
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Work Item XSS (CVE-2025-6186): This flaw allowed for the injection of malicious HTML into work item names, leading to potential account takeovers. The fix involves implementing strict validation rules for work item inputs and escaping output to mitigate XSS risks.
Permission and Authorization Enhancements:
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Project API Permissions (CVE-2025-8094): Maintainers could manipulate shared infrastructure resources beyond their intended access level, causing denial of service to other users' CI/CD pipelines. The patch refines permission checks within the project API to enforce proper access controls.
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Delete Issues Operation (CVE-2024-12303): Users with specific roles could delete issues, including confidential ones, by inviting users with a specific role. The update corrects privilege assignments to ensure that only authorized users can perform delete operations on issues.
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Jobs API Authorization (CVE-2024-10219): Authenticated users could bypass access controls to download private artifacts via specific API endpoints. The fix strengthens authorization checks within the jobs API to prevent unauthorized access.
Resource Management Improvements:
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Release Name Creation (CVE-2025-2614): Authenticated users could create specially crafted content that consumes excessive server resources, leading to denial of service. The patch introduces limits on resource allocation during release name creation to prevent such scenarios.
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Mattermost Integration (CVE-2025-1477): Unauthenticated users could send specially crafted payloads to specific integration API endpoints, causing denial of service. The update implements resource limits and input validation to mitigate this risk.
Regular Expression Complexity:
- Wiki Feature (CVE-2025-2937): Authenticated users could create denial of service conditions by sending specially crafted markdown payloads to the Wiki feature. The fix optimizes regular expression handling to prevent inefficient processing that could lead to resource exhaustion.
Additional Security Enhancements:
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Merge Request Approval Policy (CVE-2025-8770): Authenticated users with specific access could bypass merge request approval policies by manipulating approval rule identifiers. The patch enforces stricter validation of approval rules to uphold policy integrity.
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ID Token Permissions (CVE-2025-5819): Users with developer access could obtain ID tokens for protected branches under certain circumstances. The update adjusts permission assignments to ensure that ID tokens are accessible only to authorized users.
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IP Restriction Bypass (CVE-2025-2498): Users could view assigned issues from restricted groups by bypassing IP restrictions. The fix reinforces access controls to respect IP restriction settings consistently.
These patches collectively fortify GitLab's defenses against a range of security threats, ensuring a safer environment for all users.
Patch source: GitLab 18.2.2 Patch Release
Affected Systems and Versions
- GitLab Community Edition (CE) and Enterprise Edition (EE)
- Versions from 14.2 before 18.0.6
- Versions 18.1 before 18.1.4
- Versions 18.2 before 18.2.2
All configurations using the blob viewer in these versions are vulnerable.
Vendor Security History
GitLab has previously addressed similar cross-site scripting vulnerabilities in the blob viewer and related components. Notably, CVE-2021-22220 involved a stored XSS in the blob viewer for notebooks. The vendor maintains a mature vulnerability disclosure and patch management process, with coordinated releases across supported branches and detailed advisories. GitLab's response time to reported vulnerabilities is generally prompt, and its security advisories are transparent and actionable.