What is CVE-2026-56411?
xmlwf in libexpat before 2.8.2 has an integer overflow in endDoctypeDecl via NOTATION declarations.
The record classifies CVE-2026-56411 under weakness class CWE-190. Its CVSS v3 base vector states that the flaw requires local access to the host, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 106 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 6.9 — MEDIUM
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L - CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 3.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-06-21, last modified 2026-06-22
Is CVE-2026-56411 being exploited?
It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.
Affected products and versions
- libexpat project: libexpat
How to fix CVE-2026-56411
No vendor patch reference has been recorded for CVE-2026-56411 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-56411
No threat campaign in the Threadlinqs corpus currently references CVE-2026-56411, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.
Sources
Enriched from CVE.org, GitHub Security Advisories. Last verified by Threadlinqs on .