CVE-2023-43622

An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout.

This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57.

Users are recommended to upgrade to version 2.4.58, which fixes the issue.

An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout.

This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57.

Users are recommended to upgrade to version 2.4.58, which fixes the issue.

An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout. This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57. Users are recommended to upgrade to version 2.4.58, which fixes the issue.

An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout. This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57. Users are recommended to upgrade to version 2.4.58, which fixes the issue.

The mod_http2 Apache httpd module implements the HTTP2 protocol (h2+h2c) on top of libnghttp2 for httpd 2.4 servers.

Security Fix(es):

• httpd: mod_http2: DoS in HTTP/2 with initial window size 0 (CVE-2023-43622)
• mod_http2: reset requests exhaust memory (incomplete fix of CVE-2023-44487) (CVE-2023-45802)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout.

This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57.

Users are recommended to upgrade to version 2.4.58, which fixes the issue.

An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout.

This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57.

Users are recommended to upgrade to version 2.4.58, which fixes the issue.

Apache has been updated to version 2.4.58 to fix several security issues.

CVE-2023-45802: Apache HTTP Server: HTTP/2 stream memory not reclaimed right away on RST (cve.mitre.org) When a HTTP/2 stream was reset (RST frame) by a client, there was a time window were the request's memory resources were not reclaimed immediately. Instead, de-allocation was deferred to connection close. A client could send new requests and resets, keeping the connection busy and open and causing the memory footprint to keep on growing. On connection close, all resources were reclaimed, but the process might run out of memory before that. This was found by the reporter during testing of CVE-2023-44487 (HTTP/2 Rapid Reset Exploit) with their own test client. During "normal" HTTP/2 use, the probability to hit this bug is very low. The kept memory would not become noticeable before the connection closes or times out. Users are recommended to upgrade to version 2.4.58, which fixes the issue. Credits: Will Dormann of Vul Labs

CVE-2023-43622: Apache HTTP Server: DoS in HTTP/2 with initial windows size 0 (cve.mitre.org) An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout. This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57. Users are recommended to upgrade to version 2.4.58, which fixes the issue. Credits: Prof. Sven Dietrich (City University of New York)

CVE-2023-31122: mod_macro buffer over-read (cve.mitre.org) Out-of-bounds Read vulnerability in mod_macro of Apache HTTP Server. This issue affects Apache HTTP Server: through 2.4.57. Credits: David Shoon (github/davidshoon)

These are all security issues fixed in the apache2-2.4.58-1.1 package on the GA media of openSUSE Tumbleweed.

David Shoon discovered that the Apache HTTP Server mod_macro module incorrectly handled certain memory operations. A remote attacker could possibly use this issue to cause the server to crash, resulting in a denial of service. (CVE-2023-31122)

Prof. Sven Dietrich, Isa Jafarov, Prof. Heejo Lee, and Choongin Lee discovered that the Apache HTTP Server incorrectly handled certain HTTP/2 connections. A remote attacker could possibly use this issue to cause the server to consume resources, leading to a denial of service. This issue only affected Ubuntu 23.04, and Ubuntu 23.10. (CVE-2023-43622)

Will Dormann and David Warren discovered that the Apache HTTP Server incorrectly handled memory when handling HTTP/2 connections. A remote attacker could possibly use this issue to cause the server to consume resources, leading to a denial of service. (CVE-2023-45802)