Bug 2543224 (CVE-2026-102555) - CVE-2026-102555 libsoup: libsoup: Heap buffer overflow via uninitialized length in data-URI base64 decoding
Summary: CVE-2026-102555 libsoup: libsoup: Heap buffer overflow via uninitialized leng...
Keywords:
Status: NEW
Alias: CVE-2026-102555
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2543268 2543269 2543270
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-29 14:47 UTC by OSIDB Bzimport
Modified: 2026-11-11 11:19 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:83618 0 None None None 2026-10-15 15:54:07 UTC
Red Hat Product Errata RHSA-2026:93583 0 None None None 2026-11-02 08:58:17 UTC
Red Hat Product Errata RHSA-2026:98560 0 None None None 2026-11-11 11:19:23 UTC

Description OSIDB Bzimport 2026-09-29 14:47:10 UTC 
A heap buffer overflow condition was found in libsoup's soup_uri_decode_data_uri().

After percent-decoding a data URI payload marked ;base64, the code called g_base64_decode_inplace(), which measures input with strlen(). Percent-decoded content can contain embedded NUL bytes (for example data:;base64,A%00B), so the measured length was too short. g_base64_decode_inplace() returned without writing a valid output length; the uninitialized length was then stored as the size of the returned GBytes, allowing callers to read past the allocation.

Fixed upstream by decoding with g_base64_decode_step() using the real buffer length (commit e4f03226, libsoup 3.7.3).

References:
https://gitlab.gnome.org/GNOME/libsoup/-/work_items/554 (Bug 1)
https://gitlab.gnome.org/GNOME/libsoup/-/commit/e4f03226
Comment 1 Jon Orris 2026-10-15 15:54:06 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:83618 https://access.redhat.com/errata/RHSA-2026:83618
Comment 2 Jon Orris 2026-11-02 08:58:16 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:93583 https://access.redhat.com/errata/RHSA-2026:93583
Comment 3 errata-xmlrpc 2026-11-11 11:19:22 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:98560 https://access.redhat.com/errata/RHSA-2026:98560
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