CVE-2026-102557 Libsoup: libsoup: heap buffer overflow during websocket message reassembly

High 8.6 Published 29 Sep 2026 Updated 29 Oct 2026

A remote attacker can trigger heap corruption or crash applications using libsoup by sending fragmented WebSocket messages that bypass size checks.

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

What is CVE-2026-102557?

CVE-2026-102557 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 reassembling fragmented WebSocket messages into a GByteArray, libsoup did not adequately cap total message size against the limits of the underlying buffer type. A remote peer could send fragments that caused size truncation while the implementation still used the full length, leading to heap corruption or a crash.

Weakness: CWE-125

Which versions are affected by CVE-2026-102557?

It affects 2 products.

Products include Gnome Libsoup, Redhat Enterprise Linux.

How do I fix CVE-2026-102557?

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-2026-102557 being exploited?

There is no known exploitation of CVE-2026-102557 in the wild and no public exploit code.

All Redhat Enterprise Linux vulnerabilities

Sources

Also known as AZL-105546, DEBIAN-CVE-2026-102557, ECHO-8fc6-205e-57a2, GHSA-fc8r-xmg7-v58h, UBUNTU-CVE-2026-102557.