# CVE-2026-12478

## Summary

- **CVE ID:** CVE-2026-12478
- **Severity:** MEDIUM
- **CVSS Score:** 4.8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L)
- **CWE:** CWE-125
- **Published:** Jul 14, 2026
- **Last Modified:** Sep 16, 2026

## Description

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.

## Affected Products

No affected products listed.

## References

- [CNA](https://access.redhat.com/security/cve/CVE-2026-12478)
- [CNA](https://access.redhat.com/security/cve/cve-2026-0716)
- [CNA](https://bugzilla.redhat.com/show_bug.cgi?id=2489655)
- [CNA](https://gitlab.gnome.org/GNOME/libsoup/-/merge_requests/518)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.39%
- **EPSS Percentile:** 32.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._