CVE-2021-23727Public exploitNetwork attack vector

Code execution via unchecked exception-class reconstruction

Published Dec 29, 2021 · Updated Sep 16, 2024

OS command injection in Celery before 5.2.2 allows remote authenticated users to execute arbitrary code through tampered backend results. Backend.exception_to_python resolves exc_module and exc_type from failure metadata, then invokes the resolved object with exc_message without requiring an exception class. Exploitation requires access to alter a long-running task's result before a polling producer reads it, and code runs with that producer's privileges.

CVSS severity7.7
High
EPSS probability3.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Celery before 5.2.2 allows remote authenticated users to execute arbitrary code through tampered backend results. Backend.exception_to_python resolves exc_module and exc_type from failure metadata, then invokes the resolved object with exc_message without requiring an exception class. Exploitation requires access to alter a long-running task's result before a polling producer reads it, and code runs with that producer's privileges.

The record

CVE
CVE-2021-23727
Published
Dec 29, 2021
Updated
Sep 16, 2024
Vendor
Celery
Product
Celery
Classifications
CWE-77, T1059
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <5.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Celery · Celeryversion=unspecified <5.2.2

Published CVSS scores

7.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
7.5GitLab Advisory DatabaseCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
T1059Command and Scripting Interpreter

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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