CVE intelligence

CVE-2026-86143

Vulnerability intelligence

Published Sep 5, 2026Sources checked Sep 12, 2026

6.9MEDIUMCVSS out of 10

What this means

Review the available evidence

CVE-2026-86143 and is rated Medium severity with a CVSS score of 6.9. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.1%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-86143?

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.