CVE-2026-102558 Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth

High 8.6 Published 29 Sep 2026 Updated 29 Oct 2026

Heap buffer overflow in libsoup websocket handling allows attackers to execute code or cause denial of service 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-2026-102558?

CVE-2026-102558 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 max-incoming-payload-size is unlimited (0), SoupWebsocketConnection could grow its incoming GByteArray based on an attacker-controlled frame length until the length wrapped, causing a heap buffer overflow while reading frame data.

Weakness: CWE-125

Which versions are affected by CVE-2026-102558?

It affects 2 products.

Products include Gnome Libsoup, Redhat Enterprise Linux.

How do I fix CVE-2026-102558?

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-2026-102558 being exploited?

There is no known exploitation of CVE-2026-102558 in the wild and no public exploit code.

All Redhat Enterprise Linux vulnerabilities

Sources

Also known as AZL-105549, DEBIAN-CVE-2026-102558, ECHO-1ad3-2097-5734, GHSA-xxgh-qh6h-jxc2, UBUNTU-CVE-2026-102558.