Bug 2543280

Summary: CVE-2026-102558 mingw-libsoup: libsoup: Heap buffer overflow during WebSocket receive-buffer growth [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
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Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["b941a0b0-e1e1-45da-a415-8991b39583c5"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2543274    

Description Srikanth Balasubramanian 2026-09-29 16:24:32 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's WebSocket incoming receive buffer handling.

Incoming frames are accumulated in a GByteArray. With max-incoming-payload-size set to 0 (unlimited), a peer could declare a multi-GiB payload and stream it until the buffer length wrapped in g_byte_array_set_size() while the read still targeted the original offset, writing past the allocation.

Fixed by rejecting payload lengths above what the receive buffer can represent as soon as the frame header is parsed, before buffering the payload (commit 381a474f, libsoup 3.7.3). Such frames are closed as SOUP_WEBSOCKET_CLOSE_TOO_BIG.

References:
https://gitlab.gnome.org/GNOME/libsoup/-/work_items/554 (Bug 6)
https://gitlab.gnome.org/GNOME/libsoup/-/commit/381a474f