USN-6885-4: Apache HTTP Server regression

USN-6885-4: Apache HTTP Server regression
7 April 2025

USN-6885-1 introduced a regression in Apache HTTP Server.

Releases

• Ubuntu 24.10
• Ubuntu 24.04 LTS
• Ubuntu 22.04 LTS
• Ubuntu 20.04 LTS
• Ubuntu 18.04 ESM
• Ubuntu 16.04 ESM

Packages

• apache2 - Apache HTTP server

Details
USN-6885-1 fixed a vulnerability in Apache. The patch
for CVE-2024-38474 was incomplete and caused regressions.
This update provides the fix for that issue.

Original advisory details:

Orange Tsai discovered that the Apache HTTP Server mod_rewrite module
incorrectly handled certain substitutions. A remote attacker could
possibly use this issue to execute scripts in directories not directly
reachable by any URL, or cause a denial of service. Some environments
may require using the new UnsafeAllow3F flag to handle unsafe
substitutions. (CVE-2024-38474)

Update instructions
The problem can be corrected by updating your system to the following package versions:

Ubuntu 24.10

• apache2 - 2.4.62-1ubuntu1.1
  Ubuntu 24.04
• apache2 - 2.4.58-1ubuntu8.6
  Ubuntu 22.04
• apache2 - 2.4.52-1ubuntu4.14
  Ubuntu 20.04
• apache2 - 2.4.41-4ubuntu3.23
  Ubuntu 18.04
• apache2 - 2.4.29-1ubuntu4.27+esm4
  Ubuntu 16.04
• apache2 - 2.4.18-2ubuntu3.17+esm14

In general, a standard system update will make all the necessary changes.