apache http-server CVE-2021-31618 vulnerability in Apache and Other Products
Published on June 15, 2021

NULL pointer dereference on specially crafted HTTP/2 request

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Apache HTTP Server protocol handler for the HTTP/2 protocol checks received request headers against the size limitations as configured for the server and used for the HTTP/1 protocol as well. On violation of these restrictions and HTTP response is sent to the client with a status code indicating why the request was rejected. This rejection response was not fully initialised in the HTTP/2 protocol handler if the offending header was the very first one received or appeared in a a footer. This led to a NULL pointer dereference on initialised memory, crashing reliably the child process. Since such a triggering HTTP/2 request is easy to craft and submit, this can be exploited to DoS the server. This issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 only. Apache HTTP Server 2.4.47 was never released.

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Weakness Type

NULL Pointer Dereference

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions.


Products Associated with CVE-2021-31618

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Apache HTTP Server
 
Fedora Project Fedora
 
Debian Linux
 
Oracle Enterprise Manager Ops Center
 
Oracle Instantis Enterprisetrack
 
Oracle Zfs Storage Appliance Kit
 

Affected Versions

Apache Software Foundation Apache HTTP Server Version 2.4.47 is affected by CVE-2021-31618

Exploit Probability

EPSS
11.00%
Percentile
93.31%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.