Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-102559

CVE-2026-102559HIGH

Red Hat Red Hat Enterprise Linux 10 — Libsoup: libsoup: heap buffer overflow during websocket client-frame masking

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  L  L  H    8.6   .0040   33.1     —

AFFECTED
  Product                      Versions     Fixed
  Red Hat Enterprise Linux 10  unspecified  0:3.6.5-3.el10_2.20
  Red Hat Enterprise Linux 8   unspecified  0:2.62.3-19.el8_10
  Red Hat Enterprise Linux 8   unspecified  0:2.62.3-19.el8_10
  Red Hat Enterprise Linux 9   unspecified  0:2.72.0-16.el9_8.8
  Red Hat Enterprise Linux 6   unspecified  —
  Red Hat Enterprise Linux 7   unspecified  —

TIMELINE
  Sep 29  Reserved by redhat
  Sep 29  Published (CNA: redhat)
  Oct 14  PATCH SHIPPED — CVE-2026-102559 (Red Hat Enterprise Linux 9). Fixed in Red Hat Enterprise Linux 9 0:2.72.0-16.el9_8.8.

CWE-125 · CNA: redhat · CVSS v3.1 · 5 references · NVD status: Analyzed

Description

A flaw was found in libsoup. When constructing a masked WebSocket client frame for a very large outgoing payload, size values passed to GByteArray allocation APIs could be truncated while the masking routine still used the full length, causing a heap buffer overflow.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
September 29, 2026	Reserved	Reserved by redhat
September 29, 2026	Published	Published (CNA: redhat)
October 14, 2026	PATCH SHIPPED	PATCH SHIPPED — CVE-2026-102559 (Red Hat Enterprise Linux 9). Fixed in Red Hat Enterprise Linux 9 0:2.72.0-16.el9_8.8.

Affected

Affected products and packages — 6 rows
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
Red Hat	Red Hat Enterprise Linux 10	—	—	0:3.6.5-3.el10_2.20
Red Hat	Red Hat Enterprise Linux 8	—	—	0:2.62.3-19.el8_10
Red Hat	Red Hat Enterprise Linux 8	—	—	0:2.62.3-19.el8_10
Red Hat	Red Hat Enterprise Linux 9	—	—	0:2.72.0-16.el9_8.8
Red Hat	Red Hat Enterprise Linux 6	—	—	—
Red Hat	Red Hat Enterprise Linux 7	—	—	—

Weaknesses

CWE-125

References (5)

https://access.redhat.com/errata/RHSA-2026:83384 [vendor-advisory, x_refsource_REDHAT]
https://access.redhat.com/errata/RHSA-2026:83618 [vendor-advisory, x_refsource_REDHAT]
https://access.redhat.com/errata/RHSA-2026:84586 [vendor-advisory, x_refsource_REDHAT]
https://access.redhat.com/security/cve/CVE-2026-102559 [vdb-entry, x_refsource_REDHAT]
https://bugzilla.redhat.com/show_bug.cgi?id=2543285 [issue-tracking, x_refsource_REDHAT]

Authoritative record: CVE-2026-102559 at cve.org

Vendors: red hat

Weaknesses: CWE-125

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-102559 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 Monday, October 19, 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.