Bug 2543251

Summary: CVE-2026-102557 mingw-libsoup: libsoup: Heap buffer overflow during WebSocket message reassembly [fedora-all]
Product: [Fedora] Fedora Reporter: Srikanth Balasubramanian <sbalasub>
Component: mingw-libsoupAssignee: Kalev Lember <kalevlember>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: high    
Version: rawhideCC: eblima, kalevlember, marcandre.lureau, rjones
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["a30bd79c-82ec-49a8-91f8-83983a659738"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On:    
Bug Blocks: 2543231    

Description Srikanth Balasubramanian 2026-09-29 15:53:20 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