USN-4994-1: Apache HTTP Server vulnerabilities

Releases

• Ubuntu 21.04
• Ubuntu 20.10
• Ubuntu 20.04 LTS
• Ubuntu 18.04 ESM

Packages

• apache2 - Apache HTTP server

Details

Marc Stern discovered that the Apache mod_proxy_http module incorrectly
handled certain requests. A remote attacker could possibly use this issue
to cause Apache to crash, resulting in a denial of service. This issue only
affected Ubuntu 20.04 LTS, Ubuntu 20.10, and Ubuntu 21.04. (CVE-2020-13950)

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 21.04

• apache2 - 2.4.46-4ubuntu1.1
• apache2-bin - 2.4.46-4ubuntu1.1

Ubuntu 20.10

• apache2 - 2.4.46-1ubuntu1.2
• apache2-bin - 2.4.46-1ubuntu1.2

Ubuntu 20.04

• apache2 - 2.4.41-4ubuntu3.3
• apache2-bin - 2.4.41-4ubuntu3.3

Ubuntu 18.04

• apache2 - 2.4.29-1ubuntu4.16
• apache2-bin - 2.4.29-1ubuntu4.16

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

References

• CVE-2021-26691
• CVE-2021-26690
• CVE-2020-35452
• CVE-2021-30641
• CVE-2020-13950

Related notices

• USN-4994-2: apache2-suexec, apache2-doc, apache2-dev, libapache2-mod-macro, apache2-utils, libapache2-mod-proxy-html, apache2-mpm-event, apache2-data, apache2-mpm-prefork, apache2-mpm-worker, apache2, apache2-suexec-custom, apache2.2-bin, apache2-bin, apache2-suexec-pristine, apache2-mpm-itk