Jenkins Diagnostic page exposed session cookies

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2020-2103: 7.04% estimated exploitation activity in the next 30 days; percentile 94.21 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Jenkins shows various technical details about the current user on the /whoAmI page. In a previous fix, the Cookie header value containing the HTTP session ID was redacted. However, user metadata shown on this page could also include the HTTP session ID in Jenkins 2.218 and earlier, LTS 2.204.1 and earlier. This allows attackers able to exploit a cross-site scripting vulnerability to obtain the HTTP session ID value from this page. Jenkins 2.219, LTS 2.204.2 no longer prints out the affected user metadata that might contain the HTTP session ID. Additionally, we also redact values of further authentication-related HTTP headers in addition to Cookie on this page as a hardening.

Published by the source

24 May 2022, 17:07 UTC

Last modified by the source

22 Dec 2023, 13:57 UTC

Source last checked

26 Oct 2026, 16:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-4jjj-cm7q-v6hr

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# Patch Next advisory brief: CVE-2020-2103

Advisory: Jenkins Diagnostic page exposed session cookies
IDs: CVE-2020-2103, GHSA-4jjj-cm7q-v6hr
Record: https://patchnext.com/advisories/cve-2020-2103 (revision 1, source checked 26 Oct 2026, 16:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.jenkins-ci.main:jenkins-core 2.219, 2.204.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.jenkins-ci.main:jenkins-core: affected >= 2.205, < 2.219; < 2.204.2; fixed in 2.204.2, 2.219

## Suggested inspection (read-only)
- Maven org.jenkins-ci.main:jenkins-core: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.jenkins-ci.main:jenkins-core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4jjj-cm7q-v6hr (GitHub-reviewed advisory GHSA-4jjj-cm7q-v6hr lists affected ranges: Maven org.jenkins-ci.main:jenkins-core >=2.205 =0 <2.204.2)

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