CVE-2026-86143 Integer overflow in libxml2
An integer overflow in libxml2 allows negative lengths to reach write callbacks, potentially leading to code execution or denial of service.
- 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-2026-86143?
CVE-2026-86143 is a medium-severity vulnerability in Xmlsoft Libxml2, published on 5 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse causes negative lengths to reach write callbacks, aka a lack of a check for integer overflow before calling writecallback. This has security relevance for many types of uses of that length value within a callback.
Weakness: CWE-192
Which versions are affected by CVE-2026-86143?
It affects 1 product.
Products include Xmlsoft Libxml2.
How do I fix CVE-2026-86143?
Upgrade to a fixed version.
Is CVE-2026-86143 being exploited?
There is no known exploitation of CVE-2026-86143 in the wild and no public exploit code.
Other vulnerabilities in Xmlsoft Libxml2
Sources
Also known as AZL-99705, BELL-CVE-2026-86143, DEBIAN-CVE-2026-86143, ECHO-93fa-ac30-f68b, GHSA-r2q6-6v35-773j, ROOT-OS-DEBIAN-12-CVE-2026-86143 and 1 more.