CVE-2026-86143

medium

Assigned by CNA: mitre

Published 2026-09-05 · Modified 2026-09-05

Discuss on Community Propose mitigation

CVSS v3

6.9

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L

CVSS v4 NEW

—

not yet in upstream

VIR risk

6.9

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.

Predictions

Exploit likelihood

68%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

References

CWEs

CWE-192

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.