Heap Overflow in mod_xml2enc of Apache HTTP Svr 2.4.02.4.672.4.68
CVE-2026-42536 Published on June 8, 2026

Apache HTTP Server: mod_xml2enc heap overflow
Heap-based Buffer Overflow vulnerability in Apache HTTP Server with mod_xml2enc, xml2StartParse, and untrusted content This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67. Users are recommended to upgrade to version 2.4.68, which fixes the issue.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-42536 is exploitable 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 no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Timeline

reported

fixed in 2.4.x by r1934971 38 days later.

2.4.68 released 4 days later.

Weakness Types

Heap-based Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

What is a Classic Buffer Overflow Vulnerability?

The program copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. A buffer overflow condition exists when a program attempts to put more data in a buffer than it can hold, or when a program attempts to put data in a memory area outside of the boundaries of a buffer. The simplest type of error, and the most common cause of buffer overflows, is the "classic" case in which the program copies the buffer without restricting how much is copied. Other variants exist, but the existence of a classic overflow strongly suggests that the programmer is not considering even the most basic of security protections.

CVE-2026-42536 has been classified to as a Classic Buffer Overflow vulnerability or weakness.


Products Associated with CVE-2026-42536

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-42536 are published in these products:

Apache HTTP Server
 
Microsoft Http Server
 
Red Hat Enterprise Linux (RHEL)
 
Red Hat Hummingbird
 
Canonical Ubuntu Linux
 
Oracle
 

Affected Versions

Apache Software Foundation Apache HTTP Server: Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 8: Red Hat Enterprise Linux 9: Red Hat Hardened Images: Red Hat Enterprise Linux 6: Red Hat Enterprise Linux 7:

Exploit Probability

EPSS
0.50%
Percentile
38.66%

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.