Apache HTTP Server: mod_xml2enc heap overflow
Summary
| CVE | CVE-2026-42536 |
|---|---|
| State | PUBLISHED |
| Assigner | apache |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-06-08 16:16:39 UTC |
| Updated | 2026-07-02 12:17:17 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.007100000 probability, percentile 0.490340000 (date 2026-07-04)
Problem Types: CWE-122 | CWE-120 | CWE-122 CWE-122 Heap-based Buffer Overflow | CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | ADP | CVSS | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Apache | Http Server | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Apache Software Foundation | Apache HTTP Server | affected 2.4.0 2.4.67 semver | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux AppStream V. 10 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Hardened Images | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| httpd.apache.org/security/vulnerabilities_24.html | [email protected] | httpd.apache.org | Vendor Advisory |
| access.redhat.com/security/cve/CVE-2026-42536 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:34109 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| www.openwall.com/lists/oss-security/2026/06/08/9 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | Mailing List, Third Party Advisory |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42536.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Zhenpeng (Leo) Lin at depthfirst (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-04-27T12:00:00.000Z | reported |
| CNA | 2026-06-04T12:00:00.000Z | fixed in 2.4.x by r1934971 |
| CNA | 2026-06-08T12:00:00.000Z | 2.4.68 released |
| ADP | 2026-06-08T16:02:19.284Z | Reported to Red Hat. |
| ADP | 2026-06-08T15:23:46.290Z | Made public. |
Solutions
ADP: RHSA-2026:34109: Red Hat Enterprise Linux AppStream (v. 10)
Workarounds
ADP: To mitigate this vulnerability, disable the `mod_xml2enc` module if its functionality for XML internationalization is not essential. This can be done by commenting out the `LoadModule xml2enc_module modules/mod_xml2enc.so` directive in the Apache HTTP Server configuration. A service restart is required for the change to take effect. ```bash # Edit the Apache configuration file, e.g., /etc/httpd/conf.modules.d/00-base.conf # Comment out the line: # LoadModule xml2enc_module modules/mod_xml2enc.so # Reload the httpd service sudo systemctl reload httpd ``` *Note: Disabling `mod_xml2enc` will cause any configurations relying heavily on `mod_proxy_html` or raw HTML/XML encoding conversions to function incorrectly or fail. Red Hat strongly recommends upgrading to a patched version of `httpd` as soon as it becomes available for your specific RHEL channel.*