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NVD / CVE Program· CNA jenkins

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 sym

Noroxi assessment

Priority: Monitor (action score 36/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.4% (FIRST EPSS); higher than 72.7% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: org.jenkins-ci.main:jenkins-core (Maven) 2.319, 2.303.3; jenkins (Red Hat:openshift:3.11::el7) 0:2.303.3.1637698110-1.el7; jenkins-2-plugins (Red Hat:openshift:3.11::el7) 0:3.11.1637699107-1.el7.
  • Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to org.jenkins-ci.main:jenkins-core (Maven) 2.319, 2.303.3; jenkins (Red Hat:openshift:3.11::el7) 0:2.303.3.1637698110-1.el7; jenkins-2-plugins (Red Hat:openshift:3.11::el7) 0:3.11.1637699107-1.el7 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

CriticalCVSS 9.1 · v3.1—No exploit Fix available
Published
Nov 4, 2021
Updated
Jun 16, 2026
EPSS
1.4% · 72th percentile

Report tools

JSON

Action score

36

Monitor

Low priority for now.

CVSS
36 / 40 · 9.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.4%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
jenkinsjenkins

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • jenkins jenkinsbefore 2.303.3
  • jenkins jenkinsbefore 2.319

Versions reported by the vendor

Affected version ranges reported by the assigning authority (jenkins). Independent of NVD's CPE analysis and usually ahead of it.

  • Jenkins project Jenkins

    • unspecified and later · up to and including 2.318affected
    • unspecified and later · up to and including LTS 2.303.2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Mavenorg.jenkins-ci.main:jenkins-corefrom 2.304 · before 2.3192.319
Mavenorg.jenkins-ci.main:jenkins-corebefore 2.303.32.303.3
Red Hat:openshift:3.11::el7jenkinsbefore 0:2.303.3.1637698110-1.el70:2.303.3.1637698110-1.el7
Red Hat:openshift:3.11::el7jenkins-2-pluginsbefore 0:3.11.1637699107-1.el70:3.11.1637699107-1.el7
Red Hat:openshift:4.10::el7cri-obefore 0:1.23.0-92.rhaos4.10.gitdaab4d1.el70:1.23.0-92.rhaos4.10.gitdaab4d1.el7
Red Hat:openshift:4.10::el7cri-o-debuginfobefore 0:1.23.0-92.rhaos4.10.gitdaab4d1.el70:1.23.0-92.rhaos4.10.gitdaab4d1.el7
Red Hat:openshift:4.10::el7openshiftbefore 0:4.10.0-202202250816.p0.ge419edf.assembly.stream.el70:4.10.0-202202250816.p0.ge419edf.assembly.stream.el7
Red Hat:openshift:4.10::el7openshift-clientsbefore 0:4.10.0-202202160023.p0.gf93da17.assembly.stream.el70:4.10.0-202202160023.p0.gf93da17.assembly.stream.el7
Red Hat:openshift:4.10::el7openshift-clients-redistributablebefore 0:4.10.0-202202160023.p0.gf93da17.assembly.stream.el70:4.10.0-202202160023.p0.gf93da17.assembly.stream.el7
Red Hat:openshift:4.10::el7openshift-hyperkubebefore 0:4.10.0-202202250816.p0.ge419edf.assembly.stream.el70:4.10.0-202202250816.p0.ge419edf.assembly.stream.el7
Red Hat:openshift:4.10::el8coreos-installerbefore 0:0.12.0-1.rhaos4.10.el80:0.12.0-1.rhaos4.10.el8
Red Hat:openshift:4.10::el8coreos-installer-bootinfrabefore 0:0.12.0-1.rhaos4.10.el80:0.12.0-1.rhaos4.10.el8
Red Hat:openshift:4.10::el8coreos-installer-bootinfra-debuginfobefore 0:0.12.0-1.rhaos4.10.el80:0.12.0-1.rhaos4.10.el8
Red Hat:openshift:4.10::el8coreos-installer-debuginfobefore 0:0.12.0-1.rhaos4.10.el80:0.12.0-1.rhaos4.10.el8
Red Hat:openshift:4.10::el8coreos-installer-debugsourcebefore 0:0.12.0-1.rhaos4.10.el80:0.12.0-1.rhaos4.10.el8
Red Hat:openshift:4.10::el8cri-obefore 0:1.23.1-9.rhaos4.10.gitbdffb9a.el80:1.23.1-9.rhaos4.10.gitbdffb9a.el8
Red Hat:openshift:4.10::el8cri-o-debuginfobefore 0:1.23.1-9.rhaos4.10.gitbdffb9a.el80:1.23.1-9.rhaos4.10.gitbdffb9a.el8
Red Hat:openshift:4.10::el8cri-o-debugsourcebefore 0:1.23.1-9.rhaos4.10.gitbdffb9a.el80:1.23.1-9.rhaos4.10.gitbdffb9a.el8
Red Hat:openshift:4.10::el8jenkinsbefore 0:2.319.2.1643288987-1.el80:2.319.2.1643288987-1.el8
Red Hat:openshift:4.10::el8jenkins-2-pluginsbefore 0:4.10.1643404185-1.el80:4.10.1643404185-1.el8
Red Hat:openshift:4.10::el8openshiftbefore 0:4.10.0-202202250816.p0.ge419edf.assembly.stream.el80:4.10.0-202202250816.p0.ge419edf.assembly.stream.el8
Red Hat:openshift:4.10::el8openshift-clientsbefore 0:4.10.0-202202160023.p0.gf93da17.assembly.stream.el80:4.10.0-202202160023.p0.gf93da17.assembly.stream.el8
Red Hat:openshift:4.10::el8openshift-clients-redistributablebefore 0:4.10.0-202202160023.p0.gf93da17.assembly.stream.el80:4.10.0-202202160023.p0.gf93da17.assembly.stream.el8
Red Hat:openshift:4.10::el8openshift-hyperkubebefore 0:4.10.0-202202250816.p0.ge419edf.assembly.stream.el80:4.10.0-202202250816.p0.ge419edf.assembly.stream.el8

+9

Same product

jenkins: all records

Other highest-scoring records for the same primary product.

  • CVE-2024-23897Jenkins 2.441 and earlier, LTS 2.426.2 and earlier does not disable a feature of its CLI command parser that replaces an '@' character folloKEV
    99Now
  • CVE-2017-1000353Jenkins versions 2.56 and earlier as well as 2.46.1 LTS and earlier are vulnerable to an unauthenticated remote code execution.KEV
    99Now
  • CVE-2018-1000861A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153 and earlier, LTS 2.138.3 and earlier in stapler/corKEV
    98Now

Published before and after this one in the same product

  • ← EarlierCVE-2021-21685Nov 4, 2021 · Jenkins 2.318 and earlier, LTS 2.303.2 and earlier does not check agent-to-controller access to create parent directories in FilePath#mkdirs
    36Monitor
  • ← EarlierCVE-2021-21686Nov 4, 2021 · File path filters in the agent-to-controller security subsystem of Jenkins 2.318 and earlier, LTS 2.303.2 and earlier do not canonicalize pa
    33Monitor
  • Later →CVE-2021-21688Nov 4, 2021 · The agent-to-controller security check FilePath#reading(FileVisitor) in Jenkins 2.318 and earlier, LTS 2.303.2 and earlier does not reject a
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Maven:org.jenkins-ci.main:jenkins-core2.303.3Package registry (OSV)
Maven:org.jenkins-ci.main:jenkins-core2.319Package registry (OSV)
red hat:coreos-installer0:0.9.0-8.rhaos4.8.el8 · Red Hat:openshift:4.8::el8Package registry (OSV)
red hat:coreos-installer-bootinfra0:0.12.0-1.rhaos4.10.el8 · Red Hat:openshift:4.10::el8Package registry (OSV)
red hat:coreos-installer-bootinfra-debuginfo0:0.12.0-1.rhaos4.10.el8 · Red Hat:openshift:4.10::el8Package registry (OSV)
red hat:coreos-installer-debuginfo0:0.12.0-1.rhaos4.10.el8 · Red Hat:openshift:4.10::el8Package registry (OSV)
red hat:coreos-installer-debugsource0:0.12.0-1.rhaos4.10.el8 · Red Hat:openshift:4.10::el8Package registry (OSV)
red hat:cri-o0:1.23.0-92.rhaos4.10.gitdaab4d1.el7 · Red Hat:openshift:4.10::el7Package registry (OSV)
red hat:cri-o-debuginfo0:1.23.0-92.rhaos4.10.gitdaab4d1.el7 · Red Hat:openshift:4.10::el7Package registry (OSV)
red hat:cri-o-debugsource0:1.23.1-9.rhaos4.10.gitbdffb9a.el8 · Red Hat:openshift:4.10::el8Package registry (OSV)
red hat:jenkins0:2.303.3.1637597493-1.el8 · Red Hat:openshift:4.6::el8Package registry (OSV)
red hat:jenkins-2-plugins0:4.6.1637602169-1.el8 · Red Hat:openshift:4.6::el8Package registry (OSV)
red hat:openshift0:4.10.0-202202250816.p0.ge419edf.assembly.stream.el7 · Red Hat:openshift:4.10::el7Package registry (OSV)
red hat:openshift-clients0:4.10.0-202202160023.p0.gf93da17.assembly.stream.el7 · Red Hat:openshift:4.10::el7Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-862 · Missing Authorization

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records