CVE-2021-32810: crossbeam-deque is a package of work-stealing deques for building task schedulers when programming in Rust

This month

CRITICAL 9.8REMOTEUPGRADEMITIGATE

CVE-2021-32810 is a critical-severity flaw (CVSS 9.8) affecting crossbeam, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

crossbeam-deque is a package of work-stealing deques for building task schedulers when programming in Rust. In versions prior to 0.7.4 and 0.8.0, the result of the race condition is that one or more tasks in the worker queue can be popped twice instead of other tasks that are forgotten and never popped. If tasks are allocated on the heap, this can cause double free and a memory leak. If not, this still can cause a logical bug. Crates using `Steal

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.9% (top 20%)
CISA exploited list	No
Weakness	CWE-362
Published	2021-08-02
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: crossbeam project · fedoraproject

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-08-02 19:15 UTCPublished CVE record published
2026-06-17 03:53 UTCUpdated Record last modified

crossbeam project crossbeam UPGRADE

Affected: < 0.7.4 · >= 0.8.0 and < 0.8.1

Fixed in: 0.7.4, 0.8.1

Safe to downgrade to: a release before 0.8.0

1. Check installed version

apt-cache policy crossbeam || rpm -q crossbeam || crossbeam --version

2. UPGRADE to 0.7.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade crossbeam

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade crossbeam

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.8.0 (Debian / Ubuntu)

apt-cache madison crossbeam sudo apt install crossbeam=<VERSION_BEFORE_0.8.0> sudo apt-mark hold crossbeam

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list crossbeam sudo dnf downgrade crossbeam-<VERSION_BEFORE_0.8.0> sudo dnf versionlock add crossbeam

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

fedoraproject fedora MITIGATE

Affected: 34

Fixed in: no fixed release known

Safe to downgrade to: a release before 34

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-32810?

crossbeam: upgrade to 0.7.4, 0.8.1; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-32810 being exploited?

CVE-2021-32810 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-32810 affect?

CVE-2021-32810 affects crossbeam, fedora. Severity is critical (CVSS 9.8). crossbeam-deque is a package of work-stealing deques for building task schedulers when programming in Rust. In versions prior to 0.7.4 and 0.8.0, the result of the race condition is that one or more tasks in the worker queue can be popped t

How urgent is CVE-2021-32810?

Priority 59/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-23639 HIGH 8.1 UPGRADE crossbeam-utils provides atomics, synchronization primitives, scoped threads, and other utilities for concurre

References

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