CVE-2026-12478

EUVD-2026-43651
The fix for CVE-2026-0716 (commit 6ff7ef0, libsoup 3.6.6) placed the integer overflow guard inside the if (masked) block, leaving unmasked server-to-client frames unprotected. A malicious WebSocket server can send a crafted unmasked frame with a payload length near UINT64_MAX to trigger an OOB read in a libsoup-based client when max_incoming_payload_size is set to 0.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
4.8 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: 21%
Common Weakness Enumeration
References
https://access.redhat.com/security/cve/CVE-2026-12478
https://access.redhat.com/security/cve/cve-2026-0716
https://bugzilla.redhat.com/show_bug.cgi?id=2489655
https://gitlab.gnome.org/GNOME/libsoup/-/merge_requests/518