---
id: CVE-2026-113351
title: >-
  expat: expat: Denial of Service via improper memory tracking in
  XML_ParserReset (CVE-2026-113351)
summary: >-
  A flaw was found in expat. This vulnerability allows a remote attacker to
  cause a Denial of Service (DoS) by submitting a large XML document to an
  application that reuses parser instances. When the XML parser is reset using
  XML_ParserReset…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: vendor
cwe:
  - CWE-459
  - CWE-909
vendor: Red Hat
product: Red Hat Enterprise Linux 8
affected:
  - enterprise_linux 10
  - enterprise_linux 6
  - enterprise_linux 7
  - enterprise_linux 8
  - enterprise_linux 9
  - hardened_images
  - openshift_container_platform 4
published: '2026-10-20'
updated: '2026-10-20'
sourceUpdated: '2026-10-20T11:40:56+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-113351.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-113351.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-113351'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2556110'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-113351'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-113351'
  - url: 'https://github.com/libexpat/libexpat'
  - url: >-
      https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L1560
  - url: >-
      https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L860-L884
  - url: 'https://github.com/libexpat/libexpat/pull/1431'
  - url: >-
      https://www.vulncheck.com/advisories/libexpat-2.7.2-through-2.9.0-denial-of-service-via-xml-parserreset
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
ingestedAt: '2026-10-20T12:05:07.320Z'
---

## Overview

A flaw was found in expat. This vulnerability allows a remote attacker to cause a Denial of Service (DoS) by submitting a large XML document to an application that reuses parser instances. When the XML parser is reset using XML_ParserReset, it clears the direct byte count but fails to offset tracked heap allocations. Consequently, subsequent parsing operations on the reused parser fail with out-of-memory errors until the parser is completely recreated.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Hardened Images, … · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-10-20 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-113351.json)

**expat: expat: Denial of Service via improper memory tracking in XML_ParserReset** — rated Moderate by Red Hat. Released 2026-10-20.

Affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat Hardened Images
- Red Hat OpenShift Container Platform 4

No fix planned:

- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat Hardened Images

## Remediation

Out of support scope