CVE-2021-21696
CVE-2021-21696 is a critical-severity vulnerability in Jenkins with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- CVSS v2: 7.5
- EPSS exploit prediction: 2% (81st percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Jenkins
- Published:
- Last modified:
Description
Jenkins 2.318 and earlier, LTS 2.303.2 and earlier does not limit agent read/write access to the libs/ directory inside build directories when using the FilePath APIs, allowing attackers in control of agent processes to replace the code of a trusted library with a modified variant. This results in unsandboxed code execution in the Jenkins controller process.
Frequently asked questions
- What is CVE-2021-21696?
- Jenkins 2.318 and earlier, LTS 2.303.2 and earlier does not limit agent read/write access to the libs/ directory inside build directories when using the FilePath APIs, allowing attackers in control of agent processes to replace the code of a trusted library with a modified variant. This results in unsandboxed code execution in the Jenkins controller process.
- How severe is CVE-2021-21696?
- CVE-2021-21696 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-21696 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-21696?
- CVE-2021-21696 primarily affects Jenkins. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2021-21696?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2021-21696 published?
- CVE-2021-21696 was published on 2021-11-04 and last updated on 2026-06-17.
References
- http://www.openwall.com/lists/oss-security/2021/11/04/3
- https://www.jenkins.io/security/advisory/2021-11-04/#SECURITY-2423
Affected products (2)
- cpe:2.3:a:jenkins:jenkins:*:*:*:*:lts:*:*:*
- cpe:2.3:a:jenkins:jenkins:*:*:*:*:-:*:*:*
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- CVE-2021-21693 — Critical (CVSS 9.8): When creating temporary files, agent-to-controller access to create those files is only checked after they've been…
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- CVE-2021-21691 — Critical (CVSS 9.8): Creating symbolic links is possible without the 'symlink' agent-to-controller access control permission in Jenkins…
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