CVE-2021-21691

jenkins: Creating symbolic links is possible without the symlink permission

Severity Score

9.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

Creating symbolic links is possible without the 'symlink' agent-to-controller access control permission in Jenkins 2.318 and earlier, LTS 2.303.2 and earlier.

Una creación de enlaces simbólicos es posible sin el permiso de control de acceso del agente-controlador "symlink" en Jenkins versiones 2.318 y anteriores, LTS versiones 2.303.2 y anteriores

A vulnerability was found in Jenkins which failed to correctly validate permissions. This flaw allowed any user to create symbolic links regardless if they had the symlink permission. It may allow an attacker to read and write to arbitrary files on the Jenkins controller file system.

Red Hat OpenShift Container Platform is Red Hat's cloud computing Kubernetes application platform solution designed for on-premise or private cloud deployments. This advisory contains the RPM packages for Red Hat OpenShift Container Platform 4.8.22. Issues addressed include a bypass vulnerability.

*Credits: N/A

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-01-04 CVE Reserved
2021-11-04 CVE Published
2024-08-03 CVE Updated
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-59: Improper Link Resolution Before File Access ('Link Following')
CWE-276: Incorrect Default Permissions

CAPEC

References (3)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC
https://www.jenkins.io/security/advisory/2021-11-04/#SECURITY-2455	2023-11-22
https://access.redhat.com/security/cve/CVE-2021-21691	2021-11-29
https://bugzilla.redhat.com/show_bug.cgi?id=2020338	2021-11-29

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Jenkins Search vendor "Jenkins"		Jenkins Search vendor "Jenkins" for product "Jenkins"				< 2.303.3 Search vendor "Jenkins" for product "Jenkins" and version " < 2.303.3"		lts		Affected
Jenkins Search vendor "Jenkins"		Jenkins Search vendor "Jenkins" for product "Jenkins"				< 2.319 Search vendor "Jenkins" for product "Jenkins" and version " < 2.319"		-		Affected