CVE-2026-15709 Denial of service in Red Hat Enterprise Linux 10
Remote attackers can cause denial of service in applications using libsoup by sending compressed WebSocket payloads that trigger unbounded memory allocation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-15709?
CVE-2026-15709 is a high-severity denial of service 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
A flaw was found in libsoup's WebSocket implementation when using the permessage-deflate extension. The extension's decompression loop (inflate()) processes data in chunks without enforcing an upper boundary limit on the output buffer size. While libsoup limits the incoming compressed frame size via max_incoming_payload_size, it fails to track or limit memory allocation during decompression. A separate check for decompressed size (max_total_message_size) exists but executes only after inflation is complete, and it is entirely disabled by default for client connections. A remote, unauthenticated attacker can exploit this by sending a small, highly compressed payload (a decompression bomb), causing unbounded memory allocation that triggers an Out-of-Memory (OOM) crash and a Denial of Service (DoS).
Weakness: CWE-409
Which versions are affected by CVE-2026-15709?
How do I fix CVE-2026-15709?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-15709 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-15709 exists.
Sources
Also known as AZL-92411, DEBIAN-CVE-2026-15709, ECHO-3953-b7bd-49be, GHSA-gv2g-7h3v-q5f3, ROOT-OS-DEBIAN-12-CVE-2026-15709, ROOT-OS-DEBIAN-13-CVE-2026-15709 and 1 more.