No exploitation reportedFix available

CVE-2021-21687

Q: Is CVE-2021-21687 actively exploited?

Active exploitation of CVE-2021-21687 has not been confirmed. Its EPSS score was 1.4% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-21687?

CVE-2021-21687 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

No exploitation reported by the sources we read.

Published2021-11-04
Fixed in2.319 · 2.303.3
WeaknessCWE-862

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Jenkins 2.318 and earlier, LTS 2.303.2 and earlier does not check agent-to-controller access to create symbolic links when unarchiving a symbolic link in FilePath#untar.

Timeline

dates in UTC

2021-11-0417:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-21687?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-21687?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Jenkins

Branch	Affected	Fixed in	Source
2.319	< 2.319	2.319	NVD
2.x	≥ 2.304, < 2.319	2.319	OSV
2.303	< 2.303.3	2.303.3	NVD · OSV

jenkins

Branch	Affected	Fixed in	Source
2.319	< 2.319.0	2.319.0	OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Jenkins to 2.319 · 2.303.3

Advisories and patches

www.jenkins.ioVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.1read 2026-10-23
NVDCVSS 2.06.4read 2026-10-23
NVDweakness (CWE)CWE-862read 2026-10-23
FIRST EPSSEPSS score1.4 %2026-10-22
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Published: 2021-11-04
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-21687?

Jenkins 2.318 and earlier, LTS 2.303.2 and earlier does not check agent-to-controller access to create symbolic links when unarchiving a symbolic link in FilePath#untar.

Is CVE-2021-21687 actively exploited?

Active exploitation of CVE-2021-21687 has not been confirmed. Its EPSS score was 1.4% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-21687?

CVE-2021-21687 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

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