Apache HTTP Server up to 2.4.67 merge_response_headers out-of-bounds

Summaryinfo

A vulnerability labeled as problematic has been found in Apache HTTP Server up to 2.4.67. Affected by this vulnerability is the function merge_response_headers. The manipulation results in out-of-bounds. This vulnerability is cataloged as CVE-2026-43951. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Apache HTTP Server up to 2.4.67. It has been classified as problematic. Affected is the function merge_response_headers. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on availability.

The advisory is shared for download at lists.apache.org. This vulnerability is traded as CVE-2026-43951. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 06/09/2026).

The vulnerability scanner Nessus provides a plugin with the ID 319665 (Apache 2.4.x < 2.4.68 Multiple Vulnerabilities), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.4.68 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (319665) and EUVD (EUVD-2026-35093). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Web Server

Vendor

• Apache

Name

• HTTP Server

Version

• 2.4.0
• 2.4.1
• 2.4.2
• 2.4.3
• 2.4.4
• 2.4.5
• 2.4.6
• 2.4.7
• 2.4.8
• 2.4.9
• 2.4.10
• 2.4.11
• 2.4.12
• 2.4.13
• 2.4.14
• 2.4.15
• 2.4.16
• 2.4.17
• 2.4.18
• 2.4.19
• 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
• 2.4.44
• 2.4.45
• 2.4.46
• 2.4.47
• 2.4.48
• 2.4.49
• 2.4.50
• 2.4.51
• 2.4.52
• 2.4.53
• 2.4.54
• 2.4.55
• 2.4.56
• 2.4.57
• 2.4.58
• 2.4.59
• 2.4.60
• 2.4.61
• 2.4.62
• 2.4.63
• 2.4.64
• 2.4.65
• 2.4.66
• 2.4.67

License

• open-source

Website

• Vendor: https://www.apache.org/

CPE 2.3info

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• 🔒
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CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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