CVE-2026-19429 — Jenkins FilePath.untarFrom() in all versions, including those with the CVE-2026-33001…¶

Key facts

CVE-2026-19429 is a Medium (6.5) vulnerability: Jenkins FilePath.untarFrom() in all versions, including those with the CVE-2026-33001…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-19429
Severity	Medium (6.5)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-19429/

Details¶

English | 한국어

Description¶

Jenkins FilePath.untarFrom() in all versions, including those with the CVE-2026-33001 patch applied, validates symlink destinations but not targets. The CVE-2026-33001 fix enforces that the symlink file is created within the workspace boundary, but the symlink target — the path returned by te.getLinkName() and passed directly to symlinkTo() — is never validated and may point to any path on the controller filesystem. An attacker with Item/Configure permission can configure a job to extract a malicious .tar or .tar.gz archive via a tool installer or custom build step. When FilePath.untarFrom() processes the archive, it creates symlinks inside the workspace that resolve to arbitrary controller paths. By targeting the entire $JENKINS_HOME/secrets/ directory — including master.key, hudson.util.Secret, hudson.model.Secrets.xml, and any other files present — an attacker can exfiltrate all Jenkins cryptographic material through the workspace viewer (GET /job/{name}/ws/) or build artifacts. Combined with credentials.xml and per-user config.xml files, this enables offline AES-128 decryption of all {AQA...}-format credential entries, exposing in plaintext every password, API key, cloud provider secret, and SSH private key stored in the Jenkins credential store — compromising all downstream systems those credentials protect.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-19429
Type	RCE
CVSS Score	6.5

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-19429/poc.py

Usage¶

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab¶

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start¶

# Clone and navigate to CVE directory
cd CVE-2026-19429

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints¶

Application	URL	Status
Vulnerable App	http://localhost:8080	Shows vulnerability
Patched App	http://localhost:8081	Demonstrates fix

Directory Structure¶

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References¶

https://github.com/jenkinsci/jenkins
https://www.jenkins.io/security/advisory/2026-03-18/#SECURITY-3657

Generated by PoC Generator on 2026-08-11T04:02:23.767132466

Frequently asked questions¶

What is CVE-2026-19429?¶

CVE-2026-19429 is a Medium (6.5) vulnerability: Jenkins FilePath.untarFrom() in all versions, including those with the CVE-2026-33001…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-19429?¶

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2026-19429?¶

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

For authorized security testing and research only. See the full source and NVD record.