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Vulnerability · Published Sep 29, 2026 · Assigned by redhat

CVE-2026-102559Libsoup: libsoup: heap buffer overflow during websocket client-frame masking

High 8.6

In plain English

A high-severity out-of-bounds read in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.6High
Exploit odds (30 days)0.6%top 49.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8libsoup2.62.3-19.el8_10ALSA-2026:84586
AlmaLinux:9libsoup2.72.0-16.el9_8.8ALSA-2026:83384
AlmaLinux:8libsoup-devel2.62.3-19.el8_10ALSA-2026:84586
AlmaLinux:9libsoup-devel2.72.0-16.el9_8.8ALSA-2026:83384
AlmaLinux:10libsoup33.6.5-3.el10_2.20ALSA-2026:83618
AlmaLinux:10libsoup3-devel3.6.5-3.el10_2.20ALSA-2026:83618
AlmaLinux:10libsoup3-doc3.6.5-3.el10_2.20ALSA-2026:83618
Debian:12libsoup2.4no fix listedDEBIAN-CVE-2026-102559
Debian:13libsoup2.4no fix listedDEBIAN-CVE-2026-102559
Debian:12libsoup3no fix listedDEBIAN-CVE-2026-102559
Debian:13libsoup3no fix listedDEBIAN-CVE-2026-102559
Rocky Linux:8libsoup0:2.62.3-19.el8_10RLSA-2026:84586
Rocky Linux:9libsoup0:2.72.0-16.el9_8.8RLSA-2026:83384
Ubuntu:22.04:LTSlibsoup2.42.74.2-3ubuntu0.10USN-8975-1
Ubuntu:22.04:LTSlibsoup2.42.74.2-3ubuntu0.10UBUNTU-CVE-2026-102559
Ubuntu:24.04:LTSlibsoup2.42.74.3-6ubuntu1.10UBUNTU-CVE-2026-102559
Ubuntu:24.04:LTSlibsoup2.42.74.3-6ubuntu1.10USN-8975-1
Ubuntu:26.10libsoup2.4no fix listedUBUNTU-CVE-2026-102559
Ubuntu:24.04:LTSlibsoup33.4.4-5ubuntu0.10USN-8975-1
Ubuntu:24.04:LTSlibsoup33.4.4-5ubuntu0.10UBUNTU-CVE-2026-102559
Ubuntu:26.04:LTSlibsoup33.6.6-1ubuntu0.2UBUNTU-CVE-2026-102559
Ubuntu:26.04:LTSlibsoup33.6.6-1ubuntu0.2USN-8975-1
Ubuntu:26.10libsoup33.6.6-1ubuntu3.1UBUNTU-CVE-2026-102559
Ubuntu:26.10libsoup33.6.6-1ubuntu3.1USN-8975-1

Affected products (as reported)

VendorProductVersions
Red Hat Red Hat Enterprise Linux 10 see references
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support see references
Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support see references
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On see references
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support see references
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On see references
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service see references
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9 see references
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support see references
Red Hat Red Hat Enterprise Linux 6 see references

Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

References