[USN-4994-2] Apache HTTP Server vulnerabilities

========================================================================== Ubuntu Security Notice USN-4994-2 June 21, 2021
apache2 vulnerabilities ==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
– Ubuntu 16.04 ESM – Ubuntu 14.04 ESM
Summary:
Several security issues were fixed in Apache HTTP Server.
Software Description: – 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 ESM: apache2 2.4.18-2ubuntu3.17+esm1 apache2-bin 2.4.18-2ubuntu3.17+esm1
Ubuntu 14.04 ESM: apache2 2.4.7-1ubuntu4.22+esm1 apache2-bin 2.4.7-1ubuntu4.22+esm1
In general, a standard system update will make all the necessary changes.
References: ubuntu.com/security/notices/USN-4994-2 ubuntu.com/security/notices/USN-4994-1 CVE-2020-35452, CVE-2021-26690, CVE-2021-26691, CVE-2021-30641