Arch Linux Security Advisory ASA-202107-5
=========================================

Severity: High
Date    : 2021-07-01
CVE-ID  : CVE-2021-21670 CVE-2021-21671
Package : jenkins
Type    : multiple issues
Remote  : Yes
Link    : https://security.archlinux.org/AVG-2118

Summary
=======

The package jenkins before version 2.300-1 is vulnerable to multiple
issues including authentication bypass and access restriction bypass.

Resolution
==========

Upgrade to 2.300-1.

# pacman -Syu "jenkins>=2.300-1"

The problems have been fixed upstream in version 2.300.

Workaround
==========

As a workaround for CVE-2021-21670, do not grant Item/Cancel permission
to users who do not have Item/Read permission. No known workaround
exists for CVE-2021-21671.

Description
===========

- CVE-2021-21670 (access restriction bypass)

Jenkins 2.299 and earlier allows users to cancel queue items and abort
builds of jobs for which they have Item/Cancel permission even when
they do not have Item/Read permission. Jenkins 2.300 requires that
users have Item/Read permission for applicable types in addition to
Item/Cancel permission.

As a workaround on earlier versions of Jenkins, do not grant
Item/Cancel permission to users who do not have Item/Read permission.

- CVE-2021-21671 (authentication bypass)

Jenkins 2.299 and earlier does not invalidate the existing session on
login. This allows attackers to use social engineering techniques to
gain administrator access to Jenkins. Jenkins 2.300 invalidates the
existing session on login.

Impact
======

A remote attacker could login into an expired user session.
Additionally, users could cancel queue items and abort builds for which
they do not have Item/Read permission.

References
==========

https://www.jenkins.io/security/advisory/2021-06-30/#SECURITY-2278
https://github.com/jenkinsci/jenkins/commit/86b7d7e789586575522650c60d591605facb1d70
https://www.jenkins.io/security/advisory/2021-06-30/#SECURITY-2371
https://github.com/jenkinsci/jenkins/commit/25a42f3942fd9f8bd768c887c679dbc796b4fcd5
https://security.archlinux.org/CVE-2021-21670
https://security.archlinux.org/CVE-2021-21671