---
id: CVE-2026-72522
title: >-
  libexpat before 2.8.3 has an out-of-bounds read and resultant infinite loop
  because low surrogates are treated the same as high surrogates during Unicode
  processing in the *_toUtf16 functions.
summary: >-
  libexpat before 2.8.3 has an out-of-bounds read and resultant infinite loop
  because low surrogates are treated the same as high surrogates during Unicode
  processing in the *_toUtf16 functions.
severity: medium
cvss: 6.2
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-125
published: '2026-08-10'
updated: '2026-08-10'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-72522'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2053153'
    label: cve@mitre.org
  - url: 'https://github.com/libexpat/libexpat/pull/1296'
    label: cve@mitre.org
tags:
  - nvd
ingestedAt: '2026-08-10T06:39:06.682Z'
epss: 0.00184
epssPercentile: 0.07064
---

## Overview

libexpat before 2.8.3 has an out-of-bounds read and resultant infinite loop because low surrogates are treated the same as high surrogates during Unicode processing in the *_toUtf16 functions.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.