USN-4113-1 introduced a regression in Apache.
USN-4113-1 fixed vulnerabilities in the Apache HTTP server. Unfortunately, that update introduced a regression when proxying balancer manager connections in some configurations. This update fixes the problem.
17 September 2019
A security issue affects these releases of Ubuntu and its derivatives:
USN-4113-1 introduced a regression in Apache.
USN-4113-1 fixed vulnerabilities in the Apache HTTP server. Unfortunately, that update introduced a regression when proxying balancer manager connections in some configurations. This update fixes the problem.
We apologize for the inconvenience.
Original advisory details:
Stefan Eissing discovered that the HTTP/2 implementation in Apache did not properly handle upgrade requests from HTTP/1.1 to HTTP/2 in some situations. A remote attacker could use this to cause a denial of service (daemon crash). This issue only affected Ubuntu 18.04 LTS and Ubuntu 19.04. (CVE-2019-0197)
Craig Young discovered that a memory overwrite error existed in Apache when performing HTTP/2 very early pushes in some situations. A remote attacker could use this to cause a denial of service (daemon crash). This issue only affected Ubuntu 18.04 LTS and Ubuntu 19.04. (CVE-2019-10081)
Craig Young discovered that a read-after-free error existed in the HTTP/2 implementation in Apache during connection shutdown. A remote attacker could use this to possibly cause a denial of service (daemon crash) or possibly expose sensitive information. This issue only affected Ubuntu 18.04 LTS and Ubuntu 19.04. (CVE-2019-10082)
Matei Badanoiu discovered that the mod_proxy component of Apache did not properly filter URLs when reporting errors in some configurations. A remote attacker could possibly use this issue to conduct cross-site scripting (XSS) attacks. (CVE-2019-10092)
Daniel McCarney discovered that mod_remoteip component of Apache contained a stack buffer overflow when parsing headers from a trusted intermediary proxy in some situations. A remote attacker controlling a trusted proxy could use this to cause a denial of service or possibly execute arbitrary code. This issue only affected Ubuntu 19.04. (CVE-2019-10097)
Yukitsugu Sasaki discovered that the mod_rewrite component in Apache was vulnerable to open redirects in some situations. A remote attacker could use this to possibly expose sensitive information or bypass intended restrictions. (CVE-2019-10098)
Jonathan Looney discovered that the HTTP/2 implementation in Apache did not properly limit the amount of buffering for client connections in some situations. A remote attacker could use this to cause a denial of service (unresponsive daemon). This issue only affected Ubuntu 18.04 LTS and Ubuntu 19.04. (CVE-2019-9517)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
In general, a standard system update will make all the necessary changes.