# CVE-2026-86143

## Summary

- **CVE ID:** CVE-2026-86143
- **Severity:** MEDIUM
- **CVSS Score:** 6.9 (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L)
- **CWE:** CWE-192
- **Published:** Sep 5, 2026
- **Last Modified:** Sep 8, 2026

## 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.

## Affected Products

- xmlsoft — libxml2 (0)

## References

- [CNA](https://github.com/GNOME/libxml2/compare/v2.15.3...v2.15.4)
- [CNA](https://github.com/GNOME/libxml2/commit/90f293ba74d28b1d570920382e707586f68ebf35)
- [CNA](https://gitlab.gnome.org/GNOME/libxml2/-/work_items/1111)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.12%
- **EPSS Percentile:** 2.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._