Medium [CVE-2026-19429] Arbitrary file read via symlink target validation bypass
This medium-severity Red Hat Linux advisory covers CVE-2026-19429 affecting OpenShift Developer Tools and Services.
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Summary
Jenkins FilePath.untarFrom() does not validate symlink targets in extracted TAR archives, even in versions patched for CVE-2026-33001 and CVE-2026-70427. An authenticated attacker with job configuration privileges can include a malicious archive in a build step that creates workspace symlinks pointing to arbitrary files on the Jenkins controller.
By reading the secrets directory, the attacker obtains the cryptographic keys used to sign remember-me cookies, forges a valid administrator session cookie without any admin interaction, and gains access to the Script Console for remote code execution.
Jenkins 2.576 is additionally affected by a bypass of the CVE-2026-70427 blank-name check via Unicode zero-width characters (U+200B, U+200C, U+200D, U+2060, U+00AD), which Java's String.isBlank() does not recognize as whitespace. A flaw was found in Jenkins.
An authenticated remote attacker with low privileges could exploit an incomplete patch related to symlink validation during tar archive extraction. This vulnerability allows the attacker to bypass symlink target validation, enabling them to read arbitrary files on the Jenkins controller filesystem.
This could lead to the disclosure of sensitive information, such as master keys and credentials.
Affected product named by the advisory: OpenShift Developer Tools and Services.
- 2.576
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation checklist
- Until an upstream fix is available, limit Item/Configure permission on Jenkins jobs to trusted administrators only, and avoid allowing untrusted or low-privileged users to configure or run jobs that extract tar archives. If untrusted users have held Item/Configure access, rotate Jenkins credentials and the controller master key as a precaution. Where possible, restrict network access to the Jenkins controller to trusted networks.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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