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Fencer Intel
high 8.2

CVE-2026-102555 json

Libsoup: libsoup: heap buffer overflow via uninitialized length in data-uri base64 decoding

published last mo. modified 5d ago also EUVD-2026-89102

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

A flaw was found in libsoup. The soup_uri_decode_data_uri() function incorrectly treated base64 data-URI payloads as NUL-terminated strings when calling g_base64_decode_inplace(). If the percent-decoded payload contained embedded NUL bytes, the decoded length could remain uninitialized and be used as the size of the returned GBytes. This can lead to an out-of-bounds read or application crash when processing a crafted data URI.

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
  • 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-2026-102555

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

  • libsoup3 RHEL 10.2 3.6.5-3.el10_2.20

red hat advisories RHSA-2026:83618

  • 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
  • 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

suse advisories SUSE-SU-2026:24470-1SUSE-SU-2026:24368-1SUSE-SU-2026:4631-1SUSE-SU-2026:4616-1

  • libsoup openSUSE Leap 16.0 3.6.6-160000.5.1

opensuse advisories openSUSE-SU-2026:22181-1

  • libsoup3 AlmaLinux 10 3.6.5-3.el10_2.20

almalinux advisories ALSA-2026:83618

  • libsoup Azure Linux 3.0 3.4.4-18

azure linux advisories AZL-105552

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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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-2026-102555 updated cvss 8.2

libsoup: libsoup: Heap buffer overflow via uninitialized length in data-URI base64 decoding

  • Red Hat Enterprise Linux 6 libsoup
    affected: workaround, no fix planned “To mitigate this do not pass untrusted data URIs to soup_uri_decode_data_uri().”
  • Red Hat Enterprise Linux 9 libsoup
    affected: workaround, no fix available “To mitigate this do not pass untrusted data URIs to soup_uri_decode_data_uri().”
  • Red Hat Enterprise Linux AppStream (v. 10) libsoup3 3.6.5-3.el10_2.20
    fixed: vendor fix “To mitigate this do not pass untrusted data URIs to soup_uri_decode_data_uri().” RHSA-2026:83618
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) libsoup3 3.6.5-3.el10_0.19
    fixed: vendor fix “To mitigate this do not pass untrusted data URIs to soup_uri_decode_data_uri().” RHSA-2026:93583
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libsoup3-doc 3.6.5-3.el10_2.20
    fixed: vendor fix “To mitigate this do not pass untrusted data URIs to soup_uri_decode_data_uri().” 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 do not pass untrusted data URIs to soup_uri_decode_data_uri().” RHSA-2026:93583
  • Red Hat Enterprise Linux 7 libsoup Red Hat Enterprise Linux 8 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
yes
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 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 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.