Stream reassembly memory-exhaustion guard in quinn-proto can be bypassed

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

The fix for RUSTSEC-2026-0185 in 0.11.15 added a cap on the number of chunks buffered by the `Assembler` that reassembles out-of-order stream data. However, the cap was only checked inside the branch that triggers defragmentation, which only runs when the estimated over-allocation exceeds a threshold proportional to the amount of buffered data. Frames handled entirely by the unordered-read deduplication loop returned before the check ran at all. A peer sending one small gapped STREAM frame per packet (for example, 6-byte frames separated by 1-byte gaps) keeps the per-chunk overhead below the defragmentation threshold, so the cap is never evaluated and the chunk count grows until stream-level flow control stops the peer. With the default `TransportConfig` (100 concurrent unidirectional streams and a 1.25 MB stream receive window), a remote, unauthenticated peer can pin roughly 3 GB of receiver memory using about 125 MB of accounted stream data. The memory is not reclaimed until the…

Published by the source

17 Aug 2026, 12:00 UTC

Last modified by the source

12 Oct 2026, 18:15 UTC

Source last checked

23 Oct 2026, 22:04 UTC

1. Revision 1 · created · 24 Oct 2026

   Published from osv record RUSTSEC-2026-0341

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# Patch Next advisory brief: GHSA-qfwj-vfxf-92j2

Advisory: Stream reassembly memory-exhaustion guard in quinn-proto can be bypassed
IDs: GHSA-qfwj-vfxf-92j2
Record: https://patchnext.com/advisories/rustsec-2026-0341 (revision 1, source checked 23 Oct 2026, 22:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: quinn-proto 0.11.17. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io quinn-proto: affected >= 0.11.15, < 0.11.17; fixed in 0.11.17

## Suggested inspection (read-only)
- crates.io quinn-proto: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on quinn-proto.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/RUSTSEC-2026-0341 (OSV record RUSTSEC-2026-0341 lists affected ranges: crates.io quinn-proto >=0.11.15 <0.11.17 (fixed))

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