Bug 2543231 (CVE-2026-102557) - CVE-2026-102557 libsoup: libsoup: Heap buffer overflow during WebSocket message reassembly
Summary: CVE-2026-102557 libsoup: libsoup: Heap buffer overflow during WebSocket messa...
Keywords:
Status: NEW
Alias: CVE-2026-102557
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: 2543248 2543251 2543252
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-29 15:08 UTC by OSIDB Bzimport
Modified: 2026-09-29 16:54 UTC (History)
2 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-09-29 15:08:12 UTC 
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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