CVE-2026-70426: Insecure Deserialization (CVSS 9)

Description

In Remoting 3384.v60d89463d9e0 and earlier, except 3355.3357.v931d3c992987, included in Jenkins 2.575 and earlier, LTS 2.568.1 and earlier, the JEP-200 class filter is not applied to classes resolved via a fallback path in the Remoting deserialization implementation, allowing agent processes, code running on agents, and attackers with Agent/Connect permission to bypass the JEP-200 deserialization filter for classes on the Jenkins core classpath.

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CVSS v3.1 Score

9.0

CRITICAL

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Weakness Type (CWE)

CWE-502 Deserialization of Untrusted Data

References

Other References

https://www.jenkins.io/security/advisory/2026-08-05/#SECURITY-3911

Frequently Asked Questions

What is CVE-2026-70426? +

In Remoting 3384.v60d89463d9e0 and earlier, except 3355.3357.v931d3c992987, included in Jenkins 2.575 and earlier, LTS 2.568.1 and earlier, the JEP-200 class filter is not applied to classes resolved via a fallback path in the Remoting deserialization implementation, allowing agent processes, code running on agents, and attackers with Agent/Connect permission to bypass the JEP-200 deserialization filter for classes on the Jenkins core classpath. It has a CVSS v3.1 base score of 9.0 (CRITICAL).

How severe is CVE-2026-70426? +

CVE-2026-70426 has a CVSS v3.1 score of 9.0 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

How do I check if I'm vulnerable to CVE-2026-70426? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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