CVE-2026-102556 Libsoup: libsoup: heap buffer overflow from websocket pong signal type confusion

High 8.6 Published 29 Sep 2026 Updated 29 Oct 2026

Heap buffer overflow in libsoup WebSocket handling allows attackers to cause crashes or execute code via crafted Pong frames.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-102556?

CVE-2026-102556 is a high-severity memory corruption vulnerability in Redhat Enterprise Linux, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A flaw was found in libsoup. When handling an incoming WebSocket Pong frame, SoupWebsocketConnection emitted the ::pong signal with a GByteArray pointer even though the signal is declared to pass a GBytes. Applications connecting a handler that follows the documented GBytes API can trigger heap corruption or a crash upon receiving a crafted Pong.

Weakness: CWE-843

Which versions are affected by CVE-2026-102556?

It affects 2 products.

Products include Gnome Libsoup, Redhat Enterprise Linux.

How do I fix CVE-2026-102556?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-102556 being exploited?

There is no known exploitation of CVE-2026-102556 in the wild and no public exploit code.

All Redhat Enterprise Linux vulnerabilities

Sources

Also known as AZL-105555, DEBIAN-CVE-2026-102556, ECHO-6a3f-94eb-497c, GHSA-q4x2-vf8m-46j5, ROOT-OS-DEBIAN-13-CVE-2026-102556, UBUNTU-CVE-2026-102556.