CVE-2026-62963 Centrifugo: Decompression bomb DoS via permessage-deflate in unidirectional WebSocket transport
Unauthenticated attackers can cause denial of service via decompression bombs in Centrifugo's WebSocket transport when compression is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-62963?
CVE-2026-62963 is a high-severity denial of service vulnerability in centrifugal centrifugo, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Centrifugo is an open-source scalable real-time messaging server. Prior to 6.8.4, Centrifugo unidirectional WebSocket transport with uni_websocket.compression enabled enforced uni_websocket.message_size_limit against compressed wire-frame length in internal/websocket/conn.go advanceFrame, but ReadMessage used io.ReadAll after decompression without an output cap, allowing unauthenticated requests to /connection/uni_websocket to trigger large memory and CPU consumption. This issue is fixed in version 6.8.4.
Weakness: CWE-409
Which versions are affected by CVE-2026-62963?
How do I fix CVE-2026-62963?
No fix has been published for CVE-2026-62963 yet. Limit exposure of the affected software until one is available.
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-2026-62963 being exploited?
There is no known exploitation of CVE-2026-62963 in the wild and no public exploit code.
Sources
Also known as GHSA-q6mr-3g59-5m8x.