CVE-2021-21615Network attack vector

Arbitrary file read via symlink race

Published Jan 26, 2021 · Updated Aug 3, 2024

Path traversal in Jenkins 2.275 and LTS 2.263.2 allows remote authenticated users to read arbitrary files through workspace browsers. The workspace, archived-artifact, and userContent file browsers separately check and use a symlink target, letting its destination change during the interval. Exploitation requires Job/Workspace permission plus control of workspace contents, and disclosure is limited to files readable by the Jenkins process.

CVSS severity5.3
Medium
EPSS probability0.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Jenkins 2.275 and LTS 2.263.2 allows remote authenticated users to read arbitrary files through workspace browsers. The workspace, archived-artifact, and userContent file browsers separately check and use a symlink target, letting its destination change during the interval. Exploitation requires Job/Workspace permission plus control of workspace contents, and disclosure is limited to files readable by the Jenkins process.

The record

CVE
CVE-2021-21615
Published
Jan 26, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
Jenkins
Classifications
CWE-367, T1005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.275
  2. Affected versionversion=LTS 2.263.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Jenkins Project · Jenkinsversion=2.275; version=LTS 2.263.2

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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