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CVE-2026-56411VulnerabilityPublished Updated

libexpat · Xmlwf

Affects MicrosoftSource GCVE Database

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Authoritative record:CVE-2026-56411· Medium 6.9

Not known to be exploited · CVSS 6.9 Medium : upgrade to 2.8.2 when convenient.

Data as of 14 Nov 2026, 09:17 UTC

CVSS 3.1 base score
6.9Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (mitre)CVSS 3.16.9
Patch
Available – fixed in 2.8.2
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade libexpat and libexpat/libexpat to 2.8.2.

Affected software

ProductAffectedFixed in
libexpat projectlibexpatAffected
  • <2.8.2
Fixed in
  • 2.8.2
GitHublibexpat/libexpatpkg:github/libexpat/libexpatOther threatsAffected
  • <2.8.2
Fixed in
  • 2.8.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Avoid processing untrusted XML documents with affected versions until a fix is available.

Description

An integer overflow vulnerability exists in the xmlwf component of libexpat before version 2.8.2, specifically in the endDoctypeDecl function when processing NOTATION declarations. This flaw could potentially lead to unexpected behavior or memory corruption when parsing malicious XML documents.

References

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