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Fencer Vulns
medium 4.8

CVE-2026-12478 json

Libsoup: incomplete fix for cve-2026-0716: out-of-bounds read in libsoup websocket frame processing (unmasked path)

published 2026-07-14 3 mo ago modified 2026-11-05 3 d ago also EUVD-2026-43651

cvss
4.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

The fix for CVE-2026-0716 (commit 6ff7ef0, libsoup 3.6.6) placed the integer overflow guard inside the if (masked) block, leaving unmasked server-to-client frames unprotected. A malicious WebSocket server can send a crafted unmasked frame with a payload length near UINT64_MAX to trigger an OOB read in a libsoup-based client when max_incoming_payload_size is set to 0.

Patch / fix

  • libsoup3 Debian 14 3.8.0-1

debian advisories DEBIAN-CVE-2026-12478

  • 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
  • libsoup3 Ubuntu Pro 22.04 LTS 3.0.7-0ubuntu1+esm10

ubuntu advisories UBUNTU-CVE-2026-12478

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 SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Basesystem 15 SP7 3.4.4-150600.3.56.1
  • libsoup SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 3.0.4-150400.3.52.1
  • libsoup Linux Micro 6.2 3.6.6-160000.3.1
  • libsoup Linux Micro 6.0 3.4.2-17.1
  • libsoup SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.62.2-5.49.1

suse advisories SUSE-SU-2026:4690-1SUSE-SU-2026:4558-1SUSE-SU-2026:4557-1SUSE-SU-2026:23800-1SUSE-SU-2026:22920-1

  • libsoup2 openSUSE Tumbleweed 2.74.3-24.1
  • libsoup openSUSE Leap 16.0 3.6.6-160000.3.1
  • libsoup openSUSE Tumbleweed 3.6.6-7.1

opensuse advisories openSUSE-SU-2026:12084-1openSUSE-SU-2026:21871-1openSUSE-SU-2026:11316-1

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-2026-12478 updated cvss 4.8

libsoup: Incomplete fix for CVE-2026-0716: Out-of-bounds read in libsoup WebSocket frame processing (unmasked path)

  • Red Hat Enterprise Linux 7 libsoup Red Hat Enterprise Linux 8 libsoup Red Hat Enterprise Linux 9 libsoup Red Hat Enterprise Linux 10 libsoup3
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 libsoup
    not affected: vulnerable code not present

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
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness

References

Sources

Fencer Vulns 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.