CVE-2026-72522
Description
A flaw in libexpat's _toUtf16 functions mishandles Unicode low surrogates by treating them as high surrogates. An attacker can exploit the resulting out-of-bounds read to trigger an infinite loop, causing a denial of service (DoS).
Statement
A denial of service (DoS) flaw was found in libexpat's handling of Unicode surrogate pairs. An attacker providing specially crafted XML input to an application parsing untrusted data can trigger an out-of-bounds read and an infinite loop, leading to high CPU usage and system resource exhaustion.
Mitigation
Limit exposure by restricting the parsing of untrusted or unverified XML inputs, and validate incoming XML documents for malformed character sequences before processing. Additionally, enforce process-level CPU resource limits and parsing timeouts to prevent system-wide Denial of Service from infinite parsing loops.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.2 | N/A | 6.2 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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