Race Condition in tokio

Exploitation

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

CVSS

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

EPSS

• CVE-2021-45710: 1.24% estimated exploitation activity in the next 30 days; percentile 69.17 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

If a tokio::sync::oneshot channel is closed (via the oneshot::Receiver::close method), a data race may occur if the oneshot::Sender::send method is called while the corresponding oneshot::Receiver is awaited or calling tryrecv. When these methods are called concurrently on a closed channel, the two halves of the channel can concurrently access a shared memory location, resulting in a data race. This has been observed to cause memory corruption. Note that the race only occurs when both halves of the channel are used after the Receiver half has called close. Code where close is not used, or where the Receiver is not awaited and tryrecv is not called after calling close, is not affected.

Published by the source

6 Jan 2022, 22:04 UTC

Last modified by the source

13 Jun 2023, 22:01 UTC

Source last checked

26 Oct 2026, 15:37 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fg7r-2g4j-5cgr

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# Patch Next advisory brief: CVE-2021-45710

Advisory: Race Condition in tokio
IDs: CVE-2021-45710, GHSA-fg7r-2g4j-5cgr
Record: https://patchnext.com/advisories/cve-2021-45710 (revision 1, source checked 26 Oct 2026, 15:37 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tokio 1.13.1, 1.8.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io tokio: affected >= 1.9.0, < 1.13.1; >= 0.1.14, < 1.8.4; fixed in 1.8.4, 1.13.1

## Suggested inspection (read-only)
- crates.io tokio: 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 tokio.
- 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://github.com/advisories/GHSA-fg7r-2g4j-5cgr (GitHub-reviewed advisory GHSA-fg7r-2g4j-5cgr lists affected ranges: crates.io tokio >=1.9.0 =0.1.14 <1.8.4)

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