CVE-2026-84653 in Jenkins
Summary
by MITRE • 09/02/2026
Jenkins 2.579 and earlier, LTS 2.568.2 and earlier does not correctly perform permission checks in the Appearance configuration page, allowing attackers with Overall/Manage permission to modify Appearance configuration options they should not have access to.
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Analysis
by VulDB Data Team • 09/02/2026
The vulnerability identified in Jenkins versions prior to 2.579 and LTS release 2.568.2 represents a critical flaw in the application's authorization logic within the user interface layer, specifically targeting the Appearance configuration module. This security defect stems from an improper implementation of access control checks that fail to validate whether the authenticated user possesses the specific permissions required to alter appearance settings. In Jenkins, administrative privileges are granularly defined, and while users with Overall/Manage permission hold significant authority over system-wide configurations, they do not inherently possess unrestricted rights to modify every aspect of the interface without explicit authorization for those particular sub-modules. The absence of these targeted checks allows a malicious actor who has obtained or been granted Manage permissions to bypass intended restrictions and alter visual configuration options that should remain locked to higher-level administrators or specific roles defined by custom security policies.
From a technical perspective, this issue is classified under CWE-269, which denotes Improper Privilege Control. The root cause lies in the server-side handling of HTTP requests directed at the Appearance configuration endpoints. When a user submits changes to appearance settings, the application logic fails to cross-reference the current session's permissions against the specific requirements for that action. This oversight creates an authorization bypass scenario where the system trusts the request from any Manage-level user without verifying if their role includes rights to modify visual themes or interface layouts. Such flaws are particularly dangerous in enterprise environments because they undermine the principle of least privilege, allowing users with broad administrative access to perform actions outside their designated scope without triggering appropriate audit logs for unauthorized configuration changes.
The operational impact of this vulnerability extends beyond simple UI customization errors. By modifying appearance configurations, an attacker can potentially alter the look and feel of the Jenkins dashboard in ways that facilitate social engineering attacks or disrupt user workflows. For instance, changing logos, banners, or login page layouts could be used to mimic legitimate administrative interfaces for phishing purposes within a corporate network. Furthermore, if certain visual elements control visibility settings for specific plugins or dashboards, an attacker with Manage permissions could hide malicious activities from other administrators by altering the interface presentation. This undermines trust in the system's integrity and complicates forensic analysis during incident response, as standard monitoring tools may not flag changes to appearance data as high-risk events compared to direct plugin installations or credential modifications.
This vulnerability aligns closely with MITRE ATT&CK technique T1078, Valid Accounts, specifically when leveraged by an insider threat or a compromised account that has been granted excessive privileges. It also relates to T1546, Event Triggered Execution, if the appearance changes are used to trigger specific UI-based behaviors in conjunction with other vulnerabilities. The lack of proper permission checks means that even users who should be restricted from touching system aesthetics can do so freely, creating a gap in the security posture that relies heavily on correct role assignment rather than technical enforcement at the application level.
To mitigate this risk, organizations running Jenkins versions 2.578 or earlier and LTS 2.568.1 or earlier must upgrade to version 2.579 or later for standard releases, or version 2.568.3 or later for Long-Term Support branches immediately. This update includes the necessary code patches that enforce strict permission validation on all appearance configuration endpoints. In addition to upgrading, administrators should review their Jenkins security settings and ensure that Overall/Manage permissions are not granted indiscriminately. Implementing role-based access control with minimal required privileges can reduce the attack surface even if similar vulnerabilities exist in other modules. Regular auditing of user roles and monitoring for unusual changes in system configuration files will further enhance defense-in-depth strategies against privilege escalation and unauthorized modification attempts.