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CVE-2026-86143

In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse causes negative lengths to reach write…

Medium6.9EPSS 0.19%
Published
Updated
Reserved
Assigned by
mitre

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.

Timeline

  1. ID reserved

    By mitre

  2. Published

  3. · 3 days later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2026-86143, by who scored it
Scored byCVSSScoreVector
mitreCNA (assigner)3.1Medium6.9CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
NVDNVD · Analyzed3.1High7.3CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
EPSS (exploitation in 30 days)
0.19% · top 91% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: total
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.9.

Weakness

Affected products

References (3)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .