CVE-2019-15846
Published: 6 September 2019
Exim before 4.92.2 allows remote attackers to execute arbitrary code as root via a trailing backslash.
From the Ubuntu Security Team
It was discovered that Exim incorrectly handled certain decoding operations. A remote attacker could possibly use this issue to execute arbitrary commands.
Mitigation
Add - as part of the mail ACL (the ACL referenced by the main config
option "acl_smtp_mail"):
deny condition = ${if eq{\\}{${substr{-1}{1}{$tls_in_sni}}}}
deny condition = ${if eq{\\}{${substr{-1}{1}{$tls_in_peerdn}}}}
Priority
Status
| Package | Release | Status |
|---|---|---|
|
exim4 Launchpad, Ubuntu, Debian |
bionic |
Released
(4.90.1-1ubuntu1.4)
|
| disco |
Released
(4.92-4ubuntu1.3)
|
|
| trusty |
Released
(4.82-3ubuntu2.4+esm1)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only) |
|
| upstream |
Needs triage
|
|
| xenial |
Released
(4.86.2-2ubuntu2.5)
|
|
|
Patches: upstream: https://git.exim.org/exim.git/commit/2600301ba6dbac5c9d640c87007a07ee6dcea1f4 |
||
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 9.8 |
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity impact | High |
| Availability impact | High |
| Vector | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |