CVE-2026-70427
Description
A flaw was found in Jenkins. Attackers who can control agent processes can exploit this vulnerability by providing specially crafted .tar or .tar.gz archives to the Jenkins controller. This is due to unsafe handling of symbolic links with effectively empty names during archive extraction. Successful exploitation allows an attacker to write files to arbitrary locations on the file system, potentially leading to unauthorized data modification or system compromise.
Statement
Important: This flaw in Jenkins allows attackers who can control a Jenkins agent process to exploit unsafe handling of symbolic links with effectively empty names during the extraction of .tar and .tar.gz archives, writing files to arbitrary locations on the Jenkins controller's file system. This could result in arbitrary code execution and compromise of the Jenkins instance, for example by writing malicious scripts or plugins into the Jenkins home directory, but requires the attacker to already be able to run an agent process against the controller, limiting the attack surface to build infrastructure that is already at least partially trusted. This is an incomplete fix of a previously disclosed issue (CVE-2026-33001).
Mitigation
Until Jenkins is updated to a fixed version, restrict which users and systems are permitted to connect build agents to the Jenkins controller, and avoid running untrusted or externally triggered build jobs on agents that can return archives to the controller. Monitor the Jenkins controller's file system, in particular the init.groovy.d and plugins directories under the Jenkins home directory, for unauthorized changes.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | N/A | 4.3 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Changed | N/A | Unchanged |
| Confidentiality | High | N/A | None |
| Integrity Impact | High | N/A | Low |
| Availability Impact | High | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Understanding the Weakness (CWE)
Confidentiality,Integrity,Access Control
Technical Impact: Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism
An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism then an attacker may be able to bypass the mechanism.
Other
Technical Impact: Execute Unauthorized Code or Commands
Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a ".LNK" file can be uploaded like a normal file. This can enable remote execution.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
