Summary
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.
Fixed packages 1
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux · 9 | mod_http2 | 2.0.26-1.el9 |
Vulnerabilities 3
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High 7.5
HTTP/2 Stream Cancellation Attack
The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.
KEV Oct 10, 2023 -
Unscored —
Apache HTTP Server: DoS in HTTP/2 with initial windows size 0
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" a…
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Unscored —CVE-2023-45802 Public exploit
Apache HTTP Server: HTTP/2 stream memory not reclaimed right away on RST
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 t…