CVE-2026-19429

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.

Affected Software

Weaknesses

• CWE-59: CWE-59: Improper Link Resolution Before File Access ('Link Following')
• CWE-184: CWE-184: Incomplete List of Disallowed Inputs

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: total

References

• https://www.jenkins.io/security/advisory/2026-03-18/#SECURITY-3657
• https://www.jenkins.io/security/advisory/2026-08-05/
• https://github.com/jenkinsci/jenkins

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