High

Heap-based Buffer Overflow in Apache HTTP Server mod_xml2enc

IdentifiersCVE-2026-42536CWE-122· Heap-based Buffer Overflow

CVE-2026-42536 is a low-severity heap-based buffer overflow in Apache HTTP Server affecting versions 2.4.0 through 2.4.67. The issue occurs in deployments using mod_xml2enc and involves xml2StartParse when processing untrusted content. Apache identified the flaw as a heap overflow in mod_xml2enc via xml2StartParse and fixed it in the 2.4.x branch in revision r1934971, released in Apache HTTP Server 2.4.68. The available information does not include deeper root-cause details such as the exact faulty bounds calculation or specific vulnerable code path beyond the xml2StartParse/mod_xml2enc handling of untrusted input.

For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

Start free trial

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation causes heap memory corruption in the Apache HTTP Server process. Based on the disclosed vulnerability class, the most directly supported impact is process instability or child-process crash, resulting in denial of service. As with heap-based buffer overflows generally, further impact such as code execution may be possible in some environments, but the provided source material does not confirm demonstrated remote code execution for this CVE.

Mitigation

If you can’t patch tonight, do this now.

No specific workaround or mitigation for CVE-2026-42536 is provided in the supplied material. Where immediate upgrade is not possible, the practical mitigation is to reduce exposure by disabling or avoiding use of mod_xml2enc for untrusted content paths until the server can be upgraded. The authoritative remediation is upgrade to 2.4.68.

Remediation

Patch, then assume compromise.

Upgrade Apache HTTP Server to version 2.4.68 or later. Apache states that version 2.4.68 fixes this issue, and the fix is associated with revision r1934971 in the 2.4.x branch.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

9 SOURCESView more in app

cyber security newsNews

Jun 9, 2026

Apache HTTP Server 2.4.68 Released With Fix For Use-After-Free, DoS, XSS, and Buffer Overflow Flaws

A heap overflow vulnerability in Apache HTTP Server mod_xml2enc via xml2StartParse with untrusted content.

opennet ruNews

Jun 5, 2026

�� http-�� Apache 2.4.68 � �� 13 ��

Apache HTTP Server vulnerability affecting mod_xml2enc, fixed in version 2.4.68.

opennetNews

Jun 5, 2026

�� http-�� Apache 2.4.68 � �� 13 ��

Apache HTTP Server vulnerability in mod_xml2enc.

openwallNews

Apr 27, 2026

oss-security - CVE-2026-42536: Apache HTTP Server: mod_xml2enc heap overflow

A heap-based buffer overflow vulnerability in Apache HTTP Server involving mod_xml2enc and xml2StartParse when processing untrusted content.

+1 more in the timeline

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

Start free trial

Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity4

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-42536

NVD

nvd.nist.gov/vuln/detail/CVE-2026-42536

MITRE CWE · CWE-122

Heap-based Buffer Overflow

openwall.com

openwall.com/lists/oss-security/2026/06/08/9

httpd.apache.org

httpd.apache.org/security/vulnerabilities_24.html