CVE-2026-42536Network attack vector

Service interruption via stale conversion buffer length

Published Jun 8, 2026 · Updated Jun 8, 2026

Heap-based buffer overflow in mod_xml2enc in Apache HTTP Server 2.4.0 through 2.4.67 allows remote attackers to interrupt service. In fix_skipto, xml2StartParse advances the conversion-buffer pointer past skipped leading content but leaves the recorded buffer length unchanged, so later charset conversion writes beyond the allocation. Reachability requires mod_xml2enc to be loaded, xml2StartParse to be configured, and attacker-influenced content to traverse the output filter.

CVSS severity7.5
High
EPSS probability1.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Heap-based buffer overflow in mod_xml2enc in Apache HTTP Server 2.4.0 through 2.4.67 allows remote attackers to interrupt service. In fix_skipto, xml2StartParse advances the conversion-buffer pointer past skipped leading content but leaves the recorded buffer length unchanged, so later charset conversion writes beyond the allocation. Reachability requires mod_xml2enc to be loaded, xml2StartParse to be configured, and attacker-influenced content to traverse the output filter.

The record

CVE
CVE-2026-42536
Published
Jun 8, 2026
Updated
Jun 8, 2026
Vendor
The Apache Software Foundation
Product
Apache HTTP Server
Classifications
CWE-120, CWE-122, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.4.0 <=2.4.67

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HTTP Serverversion=2.4.0 <=2.4.67

Published CVSS scores

7.5Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CWE-122Heap-based Buffer Overflow
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo