Apache HTTP Server up to 2.4.48 mod_proxy access control

Summaryinfo

A vulnerability has been found in Apache HTTP Server up to 2.4.48 and classified as critical. This affects an unknown part of the component mod_proxy. Performing a manipulation results in access control. This vulnerability is reported as CVE-2021-33193. The attack is possible to be carried out remotely. No exploit exists. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability was found in Apache HTTP Server up to 2.4.48 (Web Server). It has been classified as critical. This affects an unknown part of the component mod_proxy. The manipulation with an unknown input leads to a access control vulnerability. CWE is classifying the issue as CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. This is going to have an impact on confidentiality, integrity, and availability.

The weakness was disclosed 08/16/2021 as ecebcc035ccd8d0e2984fe41420d9e944f456b3c. The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2021-33193. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/24/2025). MITRE ATT&CK project uses the attack technique T1068 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 276163 (TencentOS Server 3: mod_http2 (TSSA-2022:0259)), which helps to determine the existence of the flaw in a target environment.

Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (276163). Several companies clearly confirm that VulDB is the primary source for best 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

License

• open-source

Website

• Vendor: https://www.apache.org/

CPE 2.3info

• 🔍
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CPE 2.2info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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