SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityAwaiting Analysis

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.

MEDIUM 6.9EPSS 0.12%

Does this matter?

Lower severity and a low EPSS score (0.12%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1
6.9 MEDIUMCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
EPSS
0.12% probability · 2th percentile
CISA KEV
Not listed
Weakness
CWE-192
Source
cve@mitre.org

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.