USN-4994-2: Apache HTTP Server vulnerabilities

Releases

• Ubuntu 16.04 ESM
• Ubuntu 14.04 ESM

Packages

• apache2 - Apache HTTP server

Details

USN-4994-1 fixed several vulnerabilities in Apache. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

Antonio Morales discovered that the Apache mod_auth_digest module
incorrectly handled certain Digest nonces. A remote attacker could possibly
use this issue to cause Apache to crash, resulting in a denial of service.
(CVE-2020-35452)

Antonio Morales discovered that the Apache mod_session module incorrectly
handled certain Cookie headers. A remote attacker could possibly use this
issue to cause Apache to crash, resulting in a denial of service.
(CVE-2021-26690)

Christophe Jaillet discovered that the Apache mod_session module
incorrectly handled certain SessionHeader values. A remote attacker could
use this issue to cause Apache to crash, resulting in a denial of service,
or possibly execute arbitrary code. (CVE-2021-26691)

Christoph Anton Mitterer discovered that the new MergeSlashes configuration
option resulted in unexpected behaviour in certain situations.
(CVE-2021-30641)

Update instructions

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

Ubuntu 16.04

• apache2 - 2.4.18-2ubuntu3.17+esm1
  Available with Ubuntu Pro
• apache2-bin - 2.4.18-2ubuntu3.17+esm1
  Available with Ubuntu Pro

Ubuntu 14.04

• apache2 - 2.4.7-1ubuntu4.22+esm1
  Available with Ubuntu Pro
• apache2-bin - 2.4.7-1ubuntu4.22+esm1
  Available with Ubuntu Pro

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

References

• CVE-2021-26691
• CVE-2020-35452
• CVE-2021-30641
• CVE-2021-26690

Related notices

• USN-4994-1: apache2-bin, apache2-suexec-pristine, libapache2-mod-proxy-uwsgi, apache2, apache2-dev, apache2-data, apache2-utils, libapache2-mod-md, apache2-suexec-custom, apache2-doc, apache2-ssl-dev