CVE-2026-12478

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.

CVSS 3.1

4.8CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L

EPSS

0.2% chance of exploitation in the next 30 days; higher than 15% of CVEs (scores of 2026-10-25)

CWE

CWE-125

Published

2026-07-14

Modified

2026-10-24

Record from

the NVD, synced 2026-10-25

References

• https://access.redhat.com/security/cve/CVE-2026-12478
• https://bugzilla.redhat.com/show_bug.cgi?id=2489655
• https://gitlab.gnome.org/GNOME/libsoup/-/merge_requests/518

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