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GHSA-6xvm-j4wr-6v98

HighCVSS 8.7 / 10
Published Mar 11, 2026·Last modified Mar 13, 2026
Affected Components(0)

No affected components available

Description

Summary

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.

Details

The issue is panic-on-untrusted-input in QUIC transport parameter parsing. In quinn-proto (observed in quinn-proto 0.11.13), parsing of some transport parameters uses a fallible varint decode followed by unwrap(). For malformed/truncated parameter values, decode returns UnexpectedEnd, and unwrap() panics.

Observed output:

thread 'tokio-rt-worker' (2366474) panicked at quinn-proto/src/transport_parameters.rs:473:67:
called `Result::unwrap()` on an `Err` value: UnexpectedEnd

PoC

Reproduces against the upstream Quinn server example.

  1. Start server:
cargo run --example server -- ./
  1. Prepare PoC client environment:
python3 -m venv .venv
source .venv/bin/activate
pip install aioquic
  1. Run PoC script attack.py against server QUIC listener (default example target shown):
python attack.py

Observed output

thread 'tokio-rt-worker' (2366903) panicked at quinn-proto/src/transport_parameters.rs:473:67:
called `Result::unwrap()` on an `Err` value: UnexpectedEnd

Impact

Vulnerability type: Remote Denial of Service (panic/crash) Attack requirements: Network reachability to UDP QUIC listener Authentication/privileges: None Who is impacted: Any server/application using affected quinn/quinn-proto versions where this parse path is reachable; process-level impact depends on integration panic handling policy

This vulnerability was originally submitted by @revofusion to the Ethereum Foundation bug bounty program

Risk Scores
Base Score
8.7

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
6.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.50%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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