A recent security advisory has disclosed multiple vulnerabilities in Jenkins Core, including a high-severity stored Cross-Site Scripting (XSS) flaw that could significantly impact build environments. The vulnerabilities, tracked as CVE-2026-27099 and CVE-2026-27100, were responsibly reported through the Jenkins Bug Bounty Program sponsored by the European Commission. The most critical issue, CVE-2026-27099, affects Jenkins versions 2.550 and earlier, along with LTS versions 2.541.1 and earlier. This flaw stems from improper handling of “offline cause descriptions,” a feature that explains why a build agent goes offline. Since version 2.483, Jenkins allowed HTML content in these descriptions; however, insufficient input sanitization in vulnerable versions enabled stored XSS attacks. An attacker with Agent/Configure or Agent/Disconnect permissions could inject malicious JavaScript into the offline cause field. Because the input was not properly escaped, the malicious script could execute in the context of other users viewing the affected node, potentially leading to session compromise, credential theft, or further administrative abuse. Jenkins versions 2.551 and LTS 2.541.2 remediate the issue by properly escaping user-supplied input. Additionally, installations running Content Security Policy (CSP) enforcement in Jenkins 2.539 and later have partial protection against exploitation, though patching remains strongly recommended for full mitigation. The second vulnerability, CVE-2026-27100, is rated medium severity and affects how Jenkins processes Run Parameter values. In vulnerable versions up to 2.550 and LTS 2.541.1, users could query builds or jobs without proper authorization, allowing them to infer the existence of restricted projects. While this did not directly expose build artifacts, it enabled information disclosure that could assist further attacks within CI/CD environments. Jenkins 2.551 and LTS 2.541.2 now enforce strict validation of Run Parameter inputs to prevent unauthorized data access. Administrators are strongly advised to update immediately to mitigate risks of script injection and internal information exposure.
Silver Fox APT is presently running sophisticated targeted attacks in Taiwan that combine DLL sideloading with Bring Your Own Vulnerable Driver (BYOVD) techniques to deploy the Win...
A high-severity vulnerability identified in the widely used JavaScript PDF generation library jsPDF exposes millions of applications to PDF Object Injection attacks. Reported by GB...
A profit-driven threat actor leveraged several commercial generative AI platforms to breach more than 600 FortiGate devices across 55+ countries between January 11 and February 18,...