CVE-2026-72522 Denial of service in libexpat
An attacker can cause a denial of service via an infinite loop in libexpat's Unicode processing by exploiting an out-of-bounds read.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72522?
CVE-2026-72522 is a medium-severity denial of service vulnerability in libexpat, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-125
Which versions are affected by CVE-2026-72522?
Linux distribution packages (3)
expat Red Hat:hummingbird:1 | All versions | 0:2.8.3-0.1.hum1 |
expat-devel Red Hat:hummingbird:1 | All versions | 0:2.8.3-0.1.hum1 |
expat-static Red Hat:hummingbird:1 | All versions | 0:2.8.3-0.1.hum1 |
How do I fix CVE-2026-72522?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-72522 being exploited?
There is no known exploitation of CVE-2026-72522 in the wild and no public exploit code.
Sources
Also known as AZL-94698, BELL-CVE-2026-72522, CLSA-2026-1786976393, DEBIAN-CVE-2026-72522, ECHO-de7d-deea-1f3e, GHSA-v867-w97p-3vx2 and 8 more.