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HIGH severity

Acknowledgement extension out of memoryGHSA-cqgj-h8vf-4w59

HIGHFix: cometd/cometd#2118

GHSA-cqgj-h8vf-4w59 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in org.cometd.java:cometd-java-server-common. A fix is available for org.cometd.java:cometd-java-server-common — see the affected versions and patch details below.

Also known asCVE-2025-53114
Published
Updated
Affected
4 pkgs
Patched
4 / 4
Exploits
None indexed
Exploitation data as of Nov 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-cqgj-h8vf-4w59.

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs53th percentile — riskier than 53% of all scored CVEsHighest risk
0.00%0.39%0.79%1.18%0.4%0.7%0.7%0.7%Jul 26Nov 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

4 pkgs affected
☕org.cometd.java:cometd-java-server-common☕org.cometd.java:cometd-java-server-common☕org.cometd.java:cometd-java-server-common☕org.cometd.java:cometd-java-server-common

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Impact

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.

Patches

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

Workarounds

Disable the acknowledgement extension.

Resources

https://github.com/cometd/cometd/discussions/2116 https://github.com/cometd/cometd/issues/2117

Affected Packages

4 total 4 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.cometd.java:cometd-java-server-common≥ 5.0.0&&< 5.0.235.0.23org.cometd.java:cometd-java-server-common:5.0.23
☕Mavenorg.cometd.java:cometd-java-server-common≥ 6.0.0&&< 6.0.196.0.19org.cometd.java:cometd-java-server-common:6.0.19
☕Mavenorg.cometd.java:cometd-java-server-common≥ 7.0.0&&< 7.0.197.0.19org.cometd.java:cometd-java-server-common:7.0.19
☕Mavenorg.cometd.java:cometd-java-server-common≥ 8.0.0&&< 8.0.98.0.9org.cometd.java:cometd-java-server-common:8.0.9

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.cometd.java:cometd-java-server-common, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.cometd.java:cometd-java-server-common to 5.0.23 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cqgj-h8vf-4w59 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Impact 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: ```json { "channel": "/meta/connect", ... "ext": { "ack": 1 } } ``` The server would never clear the unacknowledged message queue, and one bad client can cause a server outage. ### Patches 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/com
O3 Security · Impact-Aware SCA

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Acknowledgement extension out of memory (High 7.5)