CVE-2026-15709

NameCVE-2026-15709
DescriptionA flaw was found in libsoup's WebSocket implementation when using the permessage-deflate extension. The extension's decompression loop (inflate()) processes data in chunks without enforcing an upper boundary limit on the output buffer size. While libsoup limits the incoming compressed frame size via max_incoming_payload_size, it fails to track or limit memory allocation during decompression. A separate check for decompressed size (max_total_message_size) exists but executes only after inflation is complete, and it is entirely disabled by default for client connections. A remote, unauthenticated attacker can exploit this by sending a small, highly compressed payload (a decompression bomb), causing unbounded memory allocation that triggers an Out-of-Memory (OOM) crash and a Denial of Service (DoS).
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1142839

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
libsoup2.4 (PTS)bullseye2.72.0-2vulnerable
bullseye (security)2.72.0-2+deb11u3vulnerable
bookworm2.74.3-1+deb12u1vulnerable
trixie2.74.3-10.1vulnerable
libsoup3 (PTS)bookworm3.2.3-0+deb12u2vulnerable
trixie3.6.5-3vulnerable
forky, sid3.6.6-1vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
libsoup2.4source(unstable)(unfixed)
libsoup3source(unstable)(unfixed)1142839

Notes

https://bugzilla.redhat.com/show_bug.cgi?id=2499922
https://gitlab.gnome.org/GNOME/libsoup/-/issues/511

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