What’s Vulnerable › Vulnerabilities

CVE-2026-86143

• Severity: high (CVSS 7.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-05 · updated 2026-09-15
• Weakness: CWE-192

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: before 2.15.4 — fixed in 2.15.4

How to fix

Upgrade to a fixed version: xmlsoft libxml2 2.15.4. Check the vendor advisory for mitigations.

References

• https://github.com/GNOME/libxml2/commit/90f293ba74d28b1d570920382e707586f68ebf35
• https://github.com/GNOME/libxml2/compare/v2.15.3...v2.15.4
• https://gitlab.gnome.org/GNOME/libxml2/-/work_items/1111

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