Improper privilege management in Exim - #VU139246
Published: July 23, 2026
Vulnerability identifier: #VU139246
CSH Severity: Low
CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-269
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to escalate privileges.
The vulnerability exists due to improper access control in .forward string expansion in pipe transports when processing a .forward file with string expansion under force_command. A local user can place crafted string expansion content in a .forward file to escalate privileges.
Exploitation requires a redirect router implementing .forward facilities for local users, a pipe transport accessible by that router, the pipe transport to have the force_command option set, and the pipe transport to be configured to run as a privileged user.
Affected software
Exim
Ubuntu
exim4 (Ubuntu package)
Ubuntu
exim4 (Ubuntu package)
Remediation
Install security update from vendor's website.
Exim - update to 4.99.5
exim4 (Ubuntu package) - addressed in versions 4.95-4ubuntu2.11, 4.97-4ubuntu4.7, 4.99.1-1ubuntu1.4
exim4 (Ubuntu package) - addressed in versions 4.95-4ubuntu2.11, 4.97-4ubuntu4.7, 4.99.1-1ubuntu1.4