Bug 2543252 - CVE-2026-102557 libsoup: libsoup: Heap buffer overflow during WebSocket message reassembly [fedora-all]
Summary: CVE-2026-102557 libsoup: libsoup: Heap buffer overflow during WebSocket messa...
Keywords:
Status: NEW
Alias: None
Product: Fedora
Classification: Fedora
Component: libsoup
Version: rawhide
Hardware: Unspecified
OS: Unspecified
high
high
Target Milestone: ---
Assignee: Gwyn Ciesla
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["a30bd79c-82ec-49a8-91f8-8...
Depends On:
Blocks: CVE-2026-102557
TreeView+ depends on / blocked
 
Reported: 2026-09-29 15:53 UTC by Srikanth Balasubramanian
Modified: 2026-09-29 15:53 UTC (History)
5 users (show)

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

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Description Srikanth Balasubramanian 2026-09-29 15:53:30 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

A heap buffer overflow was found in libsoup WebSocket fragmented-message reassembly.

Reassembled messages are stored in a GByteArray (length typed as guint). A sequence of fragments (or extension expansion) that grew the message past G_MAXINT caused g_byte_array_set_size() / related growth APIs to truncate the size while surrounding code continued to use the full length, corrupting the heap. Upstream notes interaction with older GLib (e.g. 2.70) growth behavior.

Fixed by rejecting reassembly that would exceed what a GByteArray can safely hold, independently of max-total-message-size (commit d7f074f8, libsoup 3.7.3).

References:
https://gitlab.gnome.org/GNOME/libsoup/-/work_items/554 (Bug 5)
https://gitlab.gnome.org/GNOME/libsoup/-/commit/d7f074f8
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