Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-86139

CVE-2026-86139HIGH

xmlsoft libxml2 — In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   L   L   N  U  H  H  H    7.8   .0017    5.3     —

AFFECTED
  Product  Versions     Fixed
  libxml2  unspecified  —

TIMELINE
  Sep 5   Reserved by mitre
  Sep 5   Published (CNA: mitre)
  Sep 15  RESCORED — CVE-2026-86139 (xmlsoft libxml2). CVSS 6.9 → 7.8 (NVD).

CWE-190 · CNA: mitre · CVSS v3.1 · 2 references · NVD status: Analyzed

Description

In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
September 5, 2026	Reserved	Reserved by mitre
September 5, 2026	Published	Published (CNA: mitre)
September 15, 2026	RESCORED	RESCORED — CVE-2026-86139 (xmlsoft libxml2). CVSS 6.9 → 7.8 (NVD).

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
xmlsoft	libxml2	—	—	—

Weaknesses

CWE-190

References (2)

https://github.com/GNOME/libxml2/commit/8edbbdb09f24d26a2f900141fddc2b9d014f53b0 [Patch]
https://github.com/GNOME/libxml2/compare/v2.15.3...v2.15.4 [Release Notes]

Authoritative record: CVE-2026-86139 at cve.org

Vendors: xmlsoft

Weaknesses: CWE-190

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-86139 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.