CVE-2025-29908 is a medium-severity (CVSS 5.3) CWE-407 vulnerability in io.netty.incubator:netty-incubator-codec-quic. A fix is available for io.netty.incubator:netty-incubator-codec-quic — see the affected versions and patch details below.
Netty QUIC hash collision DoS attack
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 CVE-2025-29908.
EPSS Exploitation Probability
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
io.netty.incubator:netty-incubator-codec-quicReal-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
Netty QUIC codec is a QUIC codec for netty which makes use of quiche. An issue was discovered in the codec. A hash collision vulnerability (in the hash map used to manage connections) allows remote attackers to cause a considerable CPU load on the server (a Hash DoS attack) by initiating connections with colliding Source Connection IDs (SCIDs). This vulnerability is fixed in 0.0.71.Final.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty.incubator:netty-incubator-codec-quic | all versions | 0.0.71.Finalio.netty.incubator:netty-incubator-codec-quic:0.0.71.Final |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty.incubator:netty-incubator-codec-quic, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.netty.incubator:netty-incubator-codec-quic to 0.0.71.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-29908 is resolved across your whole dependency graph.
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
Is CVE-2025-29908 in your dependencies?
Find it across Maven, including transitive dependencies.