Local privilege escalation via .forward string expansion
Published Jul 24, 2026 · Updated Jul 24, 2026
Privilege escalation in Exim 4.82 through 4.99.4 allows local users to execute .forward pipe commands with elevated privileges. The redirect and pipe-transport path accepts a string expansion from a user's .forward file when force_command is set, allowing user-controlled command behavior to reach the privileged transport. Exploitation requires a .forward redirect router, an accessible pipe transport with force_command, and that transport running as a privileged user.
Summary
What happened
Privilege escalation in Exim 4.82 through 4.99.4 allows local users to execute .forward pipe commands with elevated privileges. The redirect and pipe-transport path accepts a string expansion from a user's .forward file when force_command is set, allowing user-controlled command behavior to reach the privileged transport. Exploitation requires a .forward redirect router, an accessible pipe transport with force_command, and that transport running as a privileged user.
The record
- CVE
- CVE-2026-66141
- Published
- Jul 24, 2026
- Updated
- Jul 24, 2026
- Vendor
- LibSPF2 Project
- Product
- Exim
- Classifications
- CWE-829, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 24, 2026CVE publishedPublication date reported by the CVE source.
- Jul 24, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.82 <4.99.5
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo