CVE-2025-53114High· 7.5▾ TwilightAcknowledgement extension out of memory
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 7.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via GHSA
0.4%
0.4% → 0.7%
Bad clients that always send a fixed batch value while the server is using the acknowledgement extension can cause the unacknowledged message queue to grow indefinitely, eventually resulting in an OutOfMemoryError.
Such bad clients would always send:
{
"channel": "/meta/connect",
...
"ext": { "ack": 1 }
}
The server would never clear the unacknowledged message queue, and one bad client can cause a server outage.
5.0.x - https://github.com/cometd/cometd/pull/2168 6.0.x - https://github.com/cometd/cometd/pull/2169 8.0.x - https://github.com/cometd/cometd/pull/2118
Disable the acknowledgement extension.
https://github.com/cometd/cometd/discussions/2116 https://github.com/cometd/cometd/issues/2117
org.cometd.java:cometd-java-server-common >= 5.0.0, <= 5.0.22org.cometd.java:cometd-java-server-common >= 6.0.0, <= 6.0.18org.cometd.java:cometd-java-server-common >= 7.0.0, <= 7.0.18org.cometd.java:cometd-java-server-common >= 8.0.0, <= 8.0.8Upgrade to a patched release:
org.cometd.java:cometd-java-server-common 5.0.23org.cometd.java:cometd-java-server-common 6.0.19org.cometd.java:cometd-java-server-common 7.0.19org.cometd.java:cometd-java-server-common 8.0.9Connected by shared product, vendor, weakness, or advisory.
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