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Fencer Intel
high 8.6

CVE-2026-102559 json

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

published last mo. modified 5d ago also EUVD-2026-89104

cvss
8.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:3.6.5-3.el10_2.20
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:3.6.5-3.el10_0.19
  • Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:2.62.2-16.el7_9
  • Red Hat Red Hat Enterprise Linux 8 0:2.62.3-19.el8_10
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:2.62.3-2.el8_4.14
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:2.62.3-2.el8_4.14
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:2.62.3-2.el8_6.14
  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:2.62.3-2.el8_6.14
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:2.62.3-3.el8_8.15
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:2.62.3-3.el8_8.15
  • Red Hat Red Hat Enterprise Linux 9 0:2.72.0-16.el9_8.8
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:2.72.0-8.el9_2.18
  • Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions 0:2.72.0-8.el9_4.17
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:2.72.0-10.el9_6.14
  • libsoup3 Ubuntu 24.04 LTS 3.4.4-5ubuntu0.10
  • libsoup3 Ubuntu 26.10 3.6.6-1ubuntu3.1
  • libsoup3 Ubuntu 26.04 LTS 3.6.6-1ubuntu0.2
  • libsoup2.4 Ubuntu 22.04 LTS 2.74.2-3ubuntu0.10
  • libsoup2.4 Ubuntu 24.04 LTS 2.74.3-6ubuntu1.10
  • libsoup3 Ubuntu Pro 22.04 LTS 3.0.7-0ubuntu1+esm10
  • libsoup2.4 Ubuntu Pro 16.04 LTS 2.52.2-1ubuntu0.3+esm9
  • libsoup2.4 Ubuntu Pro 18.04 LTS 2.62.1-1ubuntu0.4+esm10

ubuntu advisories UBUNTU-CVE-2026-102559

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libsoup RHEL 8 2.62.3-19.el8_10
  • libsoup3 RHEL 10.2 3.6.5-3.el10_2.20
  • libsoup RHEL 9 2.72.0-16.el9_8.8

red hat advisories RHSA-2026:84586RHSA-2026:83618RHSA-2026:83384

  • libsoup SLES for SAP applications 16.0, SLES 16.0 3.6.6-160000.5.1
  • libsoup Linux Micro 6.0 3.4.2-159998.1.1
  • libsoup2 SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +8 more 2.74.3-150400.3.43.1
  • libsoup2 SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Basesystem 15 SP7 2.74.3-150600.4.42.1
  • libsoup SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Basesystem 15 SP7 3.4.4-150600.3.59.1
  • libsoup SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 3.0.4-150400.3.55.1
  • libsoup SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.62.2-5.49.1

suse advisories SUSE-SU-2026:24470-1SUSE-SU-2026:24368-1SUSE-SU-2026:4739-1SUSE-SU-2026:4703-1SUSE-SU-2026:4690-1SUSE-SU-2026:4631-1

  • libsoup openSUSE Leap 16.0 3.6.6-160000.5.1
  • libsoup2 openSUSE Tumbleweed 2.74.3-24.1

opensuse advisories openSUSE-SU-2026:22181-1openSUSE-SU-2026:12084-1

  • libsoup AlmaLinux 8 2.62.3-19.el8_10
  • libsoup AlmaLinux 9 2.72.0-16.el9_8.8
  • libsoup3 AlmaLinux 10 3.6.5-3.el10_2.20

almalinux advisories ALSA-2026:84586ALSA-2026:83384ALSA-2026:83618

  • libsoup Rocky Linux 8 2.62.3-19.el8_10
  • libsoup Rocky Linux 9 2.72.0-16.el9_8.8

rocky linux advisories RLSA-2026:84586RLSA-2026:83384

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-102559 updated cvss 8.6

libsoup: libsoup: Heap buffer overflow during WebSocket client-frame masking

  • Red Hat Enterprise Linux 6 libsoup
    affected: workaround, no fix planned “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.”
  • Red Hat Enterprise Linux AppStream (v. 8) libsoup-devel 2.62.3-19.el8_10, libsoup-debuginfo 2.62.3-19.el8_10, libsoup-debugsource 2.62.3-19.el8_10
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:84586
  • Red Hat Enterprise Linux AppStream (v. 9) libsoup 2.72.0-16.el9_8.8
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:83384
  • Red Hat Enterprise Linux AppStream (v. 10) libsoup3 3.6.5-3.el10_2.20
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:83618
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) libsoup-devel 2.62.3-2.el8_4.14, libsoup-debuginfo 2.62.3-2.el8_4.14, libsoup-debugsource 2.62.3-2.el8_4.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:92347
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) libsoup-devel 2.62.3-2.el8_6.14, libsoup-debuginfo 2.62.3-2.el8_6.14, libsoup-debugsource 2.62.3-2.el8_6.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93716
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) libsoup-devel 2.62.3-3.el8_8.15, libsoup-debuginfo 2.62.3-3.el8_8.15, libsoup-debugsource 2.62.3-3.el8_8.15
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93466
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) libsoup 2.72.0-8.el9_2.18
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93447
show 16 more
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) libsoup 2.72.0-8.el9_4.17
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93445
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) libsoup3 3.6.5-3.el10_0.19
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93583
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) libsoup 2.72.0-10.el9_6.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93446
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) libsoup-devel 2.62.3-2.el8_4.14, libsoup-debuginfo 2.62.3-2.el8_4.14, libsoup-debugsource 2.62.3-2.el8_4.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:92347
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) libsoup-devel 2.62.3-2.el8_6.14, libsoup-debuginfo 2.62.3-2.el8_6.14, libsoup-debugsource 2.62.3-2.el8_6.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93716
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) libsoup-devel 2.62.3-3.el8_8.15, libsoup-debuginfo 2.62.3-3.el8_8.15, libsoup-debugsource 2.62.3-3.el8_8.15
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93466
  • Red Hat Enterprise Linux BaseOS (v. 8) libsoup 2.62.3-19.el8_10
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:84586
  • Red Hat Enterprise Linux BaseOS AUS (v.8.4) libsoup 2.62.3-2.el8_4.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:92347
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) libsoup 2.62.3-2.el8_6.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93716
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) libsoup 2.62.3-3.el8_8.15
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93466
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) libsoup 2.62.3-2.el8_4.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:92347
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) libsoup 2.62.3-2.el8_6.14
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93716
  • Red Hat Enterprise Linux BaseOS TUS (v.8.8) libsoup 2.62.3-3.el8_8.15
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93466
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libsoup3-doc 3.6.5-3.el10_2.20
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:83618
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libsoup3-doc 3.6.5-3.el10_0.19
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93583
  • Red Hat Enterprise Linux Server (v. 7 ELS) libsoup 2.62.2-16.el7_9
    fixed: vendor fix “To mitigate this enforce application-level limits on outgoing WebSocket message sizes. Do not send untrusted bulk data as a single WebSocket message.” RHSA-2026:93465

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
NVD 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Affected products

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

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.