CVE-2021-21671

mediumpriority · track · 31EPSS 0.018 · 78 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.75% (78th) EPSS

CVSS 5.1 · medium

Is it mine?

9 products

Who says so?

4 sources

cnnvd · enisa_euvd · osv · nvd

EPSS · scored 2026-10-27

Jenkins 2.299 and earlier, LTS 2.289.1 and earlier does not invalidate the previous session on login.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.1–7.5

v2.05.1mediumAV:N/AC:H/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 4.9 · impact 6.4

v3.17.5highCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 1.6 · impact 5.9

v3.17.5highCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · OSV

v3.16.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

The CWE weakness classes this flaw belongs to.

Products and version ranges known to be affected.

Jenkins Project Jenkins≤ unspecified ≤LTS 2.289.1enisa_euvdEU
Jenkins Project Jenkins≤ unspecified ≤2.299enisa_euvdEU
Jenkins Project Jenkins2.266 → unspecifiedenisa_euvdEU
Jenkins Project JenkinsLTS 2.277.1 → unspecifiedenisa_euvdEU
jenkins jenkins2.266 → 2.300nvdUScpe:2.3:a:jenkins:jenkins:*:*:*:*:*:*:*:*
jenkins jenkins2.277.1 → 2.289.2nvdUScpe:2.3:a:jenkins:jenkins:*:*:*:*:*:*:*:*
Bitnami jenkins2.266.0 → 2.300.0osvUSpkg:bitnami/jenkins
Maven org.jenkins-ci.main:jenkins-core< 2.289.2osvUSpkg:maven/org.jenkins-ci.main/jenkins-core
Maven org.jenkins-ci.main:jenkins-core2.292 → 2.300osvUSpkg:maven/org.jenkins-ci.main/jenkins-core

Vendor and ecosystem advisories describing this.

GHSA-4wr9-2xc6-jmg5Session fixation vulnerability in Jenkins2022-05-24ghsa · osvUS
Jenkins 2.299 and earlier, LTS 2.289.1 and earlier does not invalidate the previous session on login. This allows attackers to use social engineering techniques to gain administrator access to Jenkins. This vulnerability was introduced in Jenkins 2.266 and LTS 2.277.1. Jenkins 2.300, LTS 2.289.2 invalidates the previous session on login. In case of problems, administrators can choose a different implementation by setting the [Java system property `hudson.security.SecurityRealm.sessionFixationProtectionMode`](https://www.jenkins.io/doc/book/managing/system-properties/#hudson-security-securityrealm-sessionfixationprotectionmode) to `2`, or disable the fix entirely by setting that system property to `0`.
BIT-jenkins-2021-216712024-03-06vendor · osvUS
Jenkins LTS 2.289.1 and earlier does not invalidate the previous session on login.

Other names and identifiers for this entity.

Which sources assert this record, and when.

published 2021-06-30modified 2026-06-17

External citations — patches, advisories, analysis.

scry

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