Topic: Apache httpd 2.4.51 GA Available

[Steffen]

Apache httpd 2.4.51 is released as GA.

ASF and Apachelounge changes : https://www.apachelounge.com/Changelog-2.4.html

Fixed critical security vulnerability in 2.4.51, see https://httpd.apache.org/security/vulnerabilities_24.html .

Note : Unfortunately it was found that the fix for the File Traversal issue in 2.4.50 was incomplete and could be bypassed.
If you use Apache HTTP Server 2.4.49 or 2.4.50 (only that versions), you should update to 2.4.51 now due to CVE-2021-42013, a nasty 0-day path traversal vulnerability.

Documentation: http://httpd.apache.org/docs/2.4/

Build with dependencies:

- openssl 1.1.1l
- nghttp2 1.44.0
- jansson 2.14
- curl 7.79.1
- apr 1.7.0
- apr-util 1.6.1
- apr-iconv 1.2.2
- zlib 1.2.11
- brotli 1.0.9
- pcre 8.45
- libxml2 2.9.12
- lua 5.2.4
- expat 2.4.1

One Redistributable for VC14, VC15 and VS16
For VC14, VC15 and VS16 there is now only one Redistributable, called Microsoft Visual C++ Redistributable for Visual Studio 2015, 2017 and 2019

When you have already installed the VC14 and/or VC15 Redistributable. Then after install of the new, the Redistributable VC14/15 is updated from 14.0x.xx/14.1x.xx to the new one 14.2x.xx , it is called Microsoft Visual C++ 2015-2019 Redistributable and you can still use VC15/14.

Note from Microsoft: Visual C++ 2015, 2017 and 2019 all share the same redistributable files.
For example, installing the Visual C++ 2015-2019 Redistributable will affect programs built with Visual C++ 2015 and 2017 also. However, installing the Visual C++ 2015 Redistributable will not replace the newer versions of the files installed by the Visual C++ 2015-2019 Redistributable.

This is different from all previous Visual C++ versions, as they each had their own distinct runtime files, not shared with other versions.

VS16, VC14 and VC15 are backward compatible.
VS16 is backward compatible to VC15/14 and VC15 backward to VC14. That means for example, a VC15/14 module can be used inside a VS16 binary (for example PHP VC15/14 as module).

Why we have a VS16 now
Maybe you noticed that we call Visual Studio C++ 2019 VS16 instead of VC16. In consultation with the PHP team we both now going to use VS16. VS16 is the version number of Visual Studio 2019.

The reason is, that VC15 is already a fictional identity, as the real VC++ version is 14.1, as you know. The new default one is now 14.2 still, not 16. Also, the version numbers move a lot faster now that in versions before VS2015. Thus, it turns out better to refer to the Visual Studio version and it's default toolset, than trying to catch up with the VC++ version which became unpredictable. Back in time, we've started to build with a preview of VS2017, which was indeed VC15, but after the GA release the version has been changed to 14.1, where we didn't catch up.


When you have hangs, slow traffic and/or when having in your log entries like Asynchronous AcceptEx failed. You can try the following settings:

AcceptFilter http none
AcceptFilter https none
EnableSendfile off
EnableMMAP off

Enjoy,

Steffen