#VU54492 Session Fixation in Jenkins and Jenkins LTS - CVE-2021-21671

Vulnerability identifier: #VU54492

Vulnerability risk: Medium

CVSSv4.0: 4.8 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-21671

CWE-ID: CWE-384

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Jenkins
Server applications / Application servers
Jenkins LTS
Server applications / Application servers

Vendor: Jenkins

Description

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to the affected product does not invalidate the existing session on login. A remote attacker can use social engineering techniques to gain administrator access to Jenkins.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Jenkins: 2.0 - 2.299

Jenkins LTS: 2.7.1 - 2.289.1

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External links
https://www.jenkins.io/security/advisory/2021-06-30/#SECURITY-2371

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.