CVE-2021-23727: This affects the package celery before 5.2.2

This month

HIGH 7.5WATCHLISTUPGRADEDOWNGRADEMITIGATE

CVE-2021-23727 is a high-severity flaw (CVSS 7.5) affecting celery, extra packages for enterprise linux, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

This affects the package celery before 5.2.2. It by default trusts the messages and metadata stored in backends (result stores). When reading task metadata from the backend, the data is deserialized. Given that an attacker can gain access to, or somehow manipulate the metadata within a celery backend, they could trigger a stored command injection vulnerability and potentially gain further access to the system.

Why this priority

High severity
Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	Low
User interaction	None
EPSS exploit chance	3.6% (top 11%)
CISA exploited list	No
Weakness	CWE-77
Published	2021-12-29
Last modified	2026-06-17

Publisher (CNA): Snyk · Vendor: celeryproject · fedoraproject

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

Am I affected?

Timeline

2021-12-29 17:15 UTCPublished CVE record published
2026-06-17 03:38 UTCUpdated Record last modified

celeryproject celery UPGRADE

Affected: < 5.2.2

Fixed in: 5.2.2

Safe to downgrade to: no unaffected older release

1. Check installed version

pip show celery

2. UPGRADE to 5.2.2

pip install --upgrade "celery>=5.2.2"

fedoraproject extra packages for enterprise linux DOWNGRADE

Affected: 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

1. Check installed version

apt-cache policy extra-packages-for-enterprise-linux || rpm -q extra-packages-for-enterprise-linux || extra-packages-for-enterprise-linux --version

2. No fixed release: DOWNGRADE to a release before 7.0 (Debian / Ubuntu)

apt-cache madison extra-packages-for-enterprise-linux sudo apt install extra-packages-for-enterprise-linux=<VERSION_BEFORE_7.0> sudo apt-mark hold extra-packages-for-enterprise-linux

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list extra-packages-for-enterprise-linux sudo dnf downgrade extra-packages-for-enterprise-linux-<VERSION_BEFORE_7.0> sudo dnf versionlock add extra-packages-for-enterprise-linux

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: 35

Fixed in: no fixed release known

Safe to downgrade to: a release before 35

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-2021-23727?

celery: upgrade to 5.2.2; extra packages for enterprise linux: downgrade or apply the listed mitigation; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-23727 being exploited?

CVE-2021-23727 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-2021-23727 affect?

CVE-2021-23727 affects celery, extra packages for enterprise linux, fedora. Severity is high (CVSS 7.5). This affects the package celery before 5.2.2. It by default trusts the messages and metadata stored in backends (result stores). When reading task metadata from the backend, the data is deserialized. Given that an attacker can gain access t

How urgent is CVE-2021-23727?

Priority 59/100. High severity; Public exploit reference; On your watchlist

References

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