CVE-2026-12478 Libsoup: incomplete fix for cve-2026-0716: out-of-bounds read in libsoup websocket frame processing (unmasked path)
A malicious WebSocket server can trigger an out-of-bounds read in libsoup clients via crafted unmasked frames when payload size limits are disabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-12478?
CVE-2026-12478 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-125
Which versions are affected by CVE-2026-12478?
Linux distribution packages (3)
libsoup SUSE:Linux Micro 6.2 | All versions | 3.6.6-160000.3.1 |
libsoup openSUSE:Leap 16.0 | All versions | 3.6.6-160000.3.1 |
libsoup openSUSE:Tumbleweed | All versions | 3.6.6-7.1 |
How do I fix CVE-2026-12478?
Apply the vendor's patch.
Is CVE-2026-12478 being exploited?
There is no known exploitation of CVE-2026-12478 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as DEBIAN-CVE-2026-12478, GHSA-6jpc-6452-qwq2, OESA-2026-3380, OESA-2026-3381, OESA-2026-3382, OESA-2026-3383 and 7 more.