# RUSTSEC-2026-0342: Zero-length DATAGRAM frames bypass the receive buffer limit in quinn-proto

> Remote attackers can cause denial of service by sending empty DATAGRAM frames that bypass buffer limits, exhausting memory in applications using quinn-proto.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Aug 2026
- **Also known as:** GHSA-2hv7-gw8g-gpq5

## What is RUSTSEC-2026-0342?

RUSTSEC-2026-0342 is a denial of service vulnerability in quinn-proto, published on 17 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

quinn-proto bounds its queue of received datagrams by charging each queued frame's payload length
against `TransportConfig::datagram_receive_buffer_size`, evicting the oldest datagrams when the
limit is exceeded. A DATAGRAM frame with an empty payload was charged zero bytes, so it never
triggered eviction and was appended to the queue, which has no other bound.

DATAGRAM frames are not subject to flow control. A peer that has completed the handshake can
therefore send a stream of empty DATAGRAM frames and grow the receiver's heap without limit until
the process is killed. An application that reads incoming datagrams but does so more slowly than
the peer sends them is still affected. Receiving datagrams is enabled by default, so all endpoints
that do not explicitly set `datagram_receive_buffer_size(None)` are affected.

The send path had the same accounting flaw: an application could enqueue an unbounded number of
empty outgoing datagrams without ever receiving `SendDatagramError::Blocked`.

The flaw was corrected in 0.11.17 by accounting for the fixed per-datagram overhead in both
directions, so that every queued datagram consumes buffer space.

Thanks to [@alexpyattaev](https://github.com/alexpyattaev) for reporting this issue.

## Which versions are affected by RUSTSEC-2026-0342?

1 open source package ship an affected version, including quinn-proto.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `quinn-proto` | crates.io | From 0.5.0 | 0.11.17 |

## How do I fix RUSTSEC-2026-0342?

Upgrade quinn-proto to 0.11.17 or later.

## Is RUSTSEC-2026-0342 being exploited?

There is no known exploitation of RUSTSEC-2026-0342 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0342 and fix it if it is affected.

What it is: RUSTSEC-2026-0342 is a denial of service vulnerability in quinn-proto, published on 17 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of RUSTSEC-2026-0342 in the wild and no public exploit code.

Affected packages and fixed versions:
- quinn-proto (crates.io): affected from 0.5.0; fixed in 0.11.17

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/RUSTSEC-2026-0342/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0342/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0342

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0342/
Summaries are generated and may contain mistakes; the official description above is the record.