Apache HTTP Server 2.4.66 Double Free via HTTP/2 (possible RCE)
CVE-2026-23918 Published on May 4, 2026
Apache HTTP Server: http2: double free and possible RCE on early reset
Double Free and possible RCE vulnerability in Apache HTTP Server with the HTTP/2 protocol.
This issue affects Apache HTTP Server: 2.4.66.
Users are recommended to upgrade to version 2.4.67, which fixes the issue.
Vulnerability Analysis
CVE-2026-23918 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Timeline
reported in PR 69899
fixed in r1930444, r1930796 1 day later.
Weakness Type
What is a Double-free Vulnerability?
The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations. When a program calls free() twice with the same argument, the program's memory management data structures become corrupted. This corruption can cause the program to crash or, in some circumstances, cause two later calls to malloc() to return the same pointer. If malloc() returns the same value twice and the program later gives the attacker control over the data that is written into this doubly-allocated memory, the program becomes vulnerable to a buffer overflow attack.
CVE-2026-23918 has been classified to as a Double-free vulnerability or weakness.
Products Associated with CVE-2026-23918
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Affected Versions
Apache Software Foundation Apache HTTP Server Version 2.4.66 is affected by CVE-2026-23918Exploit Probability
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.