Apache HTTP Server up to 2.4.43 mod_http2 request smuggling

Summaryinfo

A vulnerability classified as critical was found in Apache HTTP Server. This affects an unknown function of the component mod_http2. Executing a manipulation can lead to request smuggling. This vulnerability is handled as CVE-2020-11993. The attack can be executed remotely. There is not any exploit available. Changing the configuration settings is recommended.

Detailsinfo

A vulnerability has been found in Apache HTTP Server (Web Server) and classified as critical. This vulnerability affects an unknown function of the component mod_http2. The manipulation with an unknown input leads to a request smuggling vulnerability. The CWE definition for the vulnerability is CWE-444. The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. As an impact it is known to affect availability. CVE summarizes:

Apache HTTP Server versions 2.4.20 to 2.4.43 When trace/debug was enabled for the HTTP/2 module and on certain traffic edge patterns, logging statements were made on the wrong connection, causing concurrent use of memory pools. Configuring the LogLevel of mod_http2 above "info" will mitigate this vulnerability for unpatched servers.

The weakness was released 08/07/2020 (Website). The advisory is shared for download at security.gentoo.org. This vulnerability was named CVE-2020-11993 since 04/21/2020. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 05/01/2025).

The vulnerability scanner Nessus provides a plugin with the ID 210018 (Amazon Linux AMI : httpd24 (ALAS-2024-1951)), which helps to determine the existence of the flaw in a target environment.

It is possible to mitigate the problem by applying the configuration setting .

The vulnerability is also documented in the vulnerability database at Tenable (210018). Entries connected to this vulnerability are available at VDB-159374, VDB-159375 and VDB-159399. VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Web Server

Vendor

• Apache

Name

• HTTP Server

Version

• 2.4.20
• 2.4.21
• 2.4.22
• 2.4.23
• 2.4.24
• 2.4.25
• 2.4.26
• 2.4.27
• 2.4.28
• 2.4.29
• 2.4.30
• 2.4.31
• 2.4.32
• 2.4.33
• 2.4.34
• 2.4.35
• 2.4.36
• 2.4.37
• 2.4.38
• 2.4.39
• 2.4.40
• 2.4.41
• 2.4.42
• 2.4.43

License

• open-source

Website

• Vendor: https://www.apache.org/

CPE 2.3info

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CPE 2.2info

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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