Apache HTTP Server 2.4.66: OOB Read in mod_proxy_ajp (fixed 2.4.67)
CVE-2026-33857 Published on May 4, 2026
Apache HTTP Server: Off-by-one OOB reads in AJP getter functions
Out-of-bounds Read vulnerability in mod_proxy_ajp of
Apache HTTP Server.
This issue affects Apache HTTP Server: through 2.4.66.
Users are recommended to upgrade to version 2.4.67, which fixes the issue.
Vulnerability Analysis
CVE-2026-33857 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, a small impact on integrity and availability.
Timeline
Reported
fixed by r1933341 in 2.4.x 45 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-2026-33857
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Affected Versions
Apache Software Foundation Apache HTTP Server:- Before and including 2.4.66 is affected.