Jenkins - FilePath.untarFrom() Symlink Target Validation Bypass and Blank-Name Check Bypass (Arbitrary File Read)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-19429
StatePUBLISHED
AssignerTuranSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-10 13:17:58 UTC
Updated2026-08-11 08:17:20 UTC
DescriptionJenkins FilePath.untarFrom() does not validate symlink targets in extracted TAR archives, even in versions patched for CVE-2026-33001 and CVE-2026-70427. An authenticated attacker with job configuration privileges can include a malicious archive in a build step that creates workspace symlinks pointing to arbitrary files on the Jenkins controller. By reading the secrets directory, the attacker obtains the cryptographic keys used to sign remember-me cookies, forges a valid administrator session cookie without any admin interaction, and gains access to the Script Console for remote code execution. Jenkins 2.576 is additionally affected by a bypass of the CVE-2026-70427 blank-name check via Unicode zero-width characters (U+200B, U+200C, U+200D, U+2060, U+00AD), which Java's String.isBlank() does not recognize as whitespace.

Risk And Classification

Primary CVSS: v4.0 9.4 CRITICAL from 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-59 | CWE-184 | CWE-59 CWE-59: Improper Link Resolution Before File Access ('Link Following') | CWE-184 CWE-184: Incomplete List of Disallowed Inputs

VersionSourceTypeScoreSeverityVector
4.0309f9ea4-e3e9-4c6c-b79d-e8eb01244f2cSecondary9.4CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/C...
4.0CNACVSS9.4CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
3.1309f9ea4-e3e9-4c6c-b79d-e8eb01244f2cSecondary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Confidentiality
High
Integrity
High
Availability
High
Sub Conf.
High
Sub Integrity
High
Sub Availability
High

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Jenkins Project Jenkins affected 1.0 2.576 weekly Not specified
CNA Jenkins Project Jenkins affected 1.0 2.568.2 LTS Not specified

References

ReferenceSourceLinkTags
www.jenkins.io/security/advisory/2026-08-05 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c www.jenkins.io
github.com/jenkinsci/jenkins 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c github.com
www.jenkins.io/security/advisory/2026-03-18 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c www.jenkins.io
www.jenkins.io/security/advisories/2026-03-19 MITRE www.jenkins.io
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Jamshed Yergashvoyev (CVE GUY | TuranSec) (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-04-04T00:00:00.000ZVulnerability discovered via patch-diff analysis of CVE-2026-33001 fix
CNA2026-08-05T00:00:00.000ZRe-verified against Jenkins 2.557 and LTS 2.555.3 — still unpatched
CNA2026-08-10T12:00:00.000ZPublic disclosure (90-day window exceeded)
CNA2026-08-11T00:00:00.000ZAdditional variant confirmed: CVE-2026-70427 blank-name patch bypass via Unicode zero-width characters (U+200B/U+200C/U+200D/U+2060/U+00AD) on Jenkins 2.576
CNA2026-08-11T08:00:00.000ZFull impact confirmed: secrets directory read enables remember-me cookie forgery and unauthenticated admin RCE with zero admin interaction

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