Apache HTTP Server <= 2.4.67: OOB Read in mod_headers/mod_mime
CVE-2026-43951 Published on June 8, 2026
Apache HTTP Server: OOB Read in `merge_response_headers` can cause crash
Out-of-bounds Read vulnerability in Apache HTTP Server with mod_headers and mod_mime and multiple response languages.
This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67.
Vulnerability Analysis
CVE-2026-43951 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Timeline
reported
fixed in 2.4.x by r1935006 39 days later.
2.4.68 released 3 days later.
Weakness Type
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
Products Associated with CVE-2026-43951
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Affected Versions
Apache Software Foundation Apache HTTP Server:- Version 2.4.0, <= 2.4.67 is affected.
Exploit 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.