Quinn affected by unauthenticated remote DoS via panic in QUIC transport parameter parsing

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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.

Source published

10 Mar 2026 21:04:36 UTC

Source modified

25 Aug 2026 12:05:46 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 8.7 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

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.

Source published

Mar 10, 2026, 9:04:36 PM (timezone not stated)

Source modified

Aug 25, 2026, 12:05:46 PM (timezone not stated)

Saved here

15 Nov 2026 12:07:18 UTC

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EUVD CVSS 4.0 · 8.7 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

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.

Source published

10 Mar 2026 22:16:18 UTC

Source modified

25 Aug 2026 13:18:17 UTC

Saved here

25 Oct 2026 07:19:14 UTC

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CVSS 4.0 · [email protected] · Secondary · 8.7 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

### 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 -- ./ ``` 2. Prepare PoC client environment: ``` python3 -m venv .venv source .venv/bin/activate pip install aioquic ``` 3. Run PoC script [attack.py](https://github.com/user-attachments/files/25741713/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

Source published

11 Mar 2026 00:09:19 UTC

Source modified

10 Sep 2026 03:50:37 UTC

Saved here

24 Oct 2026 13:19:54 UTC

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GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · 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

Publisher rating · HIGH

Receiving QUIC transport parameters containing invalid values could lead to a panic. Unfortunately the maintainers did not properly assess usage of `unwrap()` calls in the transport parameters parsing code, and we did not have sufficient fuzzing coverage to find this issue. We have since added a fuzzing target to cover this code path.

Source published

9 Mar 2026 12:00:00 UTC

Source modified

14 Mar 2026 07:30:14 UTC

Saved here

24 Oct 2026 13:19:54 UTC

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OSV · upstream source license applies

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Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V4 · 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