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Ubuntu Security Notice USN-5090-2
September 27, 2021

apache2 vulnerabilities
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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-5090-1 fixed several vulnerabilities in Apache. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

 It was discovered that the Apache HTTP Server incorrectly handled certain
 malformed requests. A remote attacker could possibly use this issue to
 cause the server to crash, resulting in a denial of service.
 (CVE-2021-34798)

 It was discovered that the Apache HTTP Server incorrectly handled escaping
 quotes. If the server was configured with third-party modules, a remote
 attacker could use this issue to cause the server to crash, resulting in a
 denial of service, or possibly execute arbitrary code. (CVE-2021-39275)

 It was discovered that the Apache mod_proxy module incorrectly handled
 certain request uri-paths. A remote attacker could possibly use this issue
 to cause the server to forward requests to arbitrary origin servers.
 (CVE-2021-40438)

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+esm2
  apache2-bin                     2.4.18-2ubuntu3.17+esm2

Ubuntu 14.04 ESM:
  apache2                         2.4.7-1ubuntu4.22+esm2
  apache2-bin                     2.4.7-1ubuntu4.22+esm2

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

References:
  https://ubuntu.com/security/notices/USN-5090-2
  https://ubuntu.com/security/notices/USN-5090-1
  CVE-2021-34798, CVE-2021-39275, CVE-2021-40438