CVE-2021-21264Network attack vector

Authenticated PHP execution via Twig sandbox escape

Published May 3, 2021 · Updated Aug 3, 2024

Sandbox escape in October CMS 1.0.471 and 1.1.1 allows remote authenticated users to execute arbitrary PHP through crafted Twig code. The Twig SecurityPolicy blocklist omits Eloquent and Halcyon insert, update, and delete methods, allowing sandboxed templates to perform forbidden data operations and escape the intended restriction. Exploitation requires page, layout, or partial management permission and matters when cms.enableSafeMode is enabled to prohibit PHP execution.

CVSS severity5.2
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sandbox escape in October CMS 1.0.471 and 1.1.1 allows remote authenticated users to execute arbitrary PHP through crafted Twig code. The Twig SecurityPolicy blocklist omits Eloquent and Halcyon insert, update, and delete methods, allowing sandboxed templates to perform forbidden data operations and escape the intended restriction. Exploitation requires page, layout, or partial management permission and matters when cms.enableSafeMode is enabled to prohibit PHP execution.

The record

CVE
CVE-2021-21264
Published
May 3, 2021
Updated
Aug 3, 2024
Vendor
October CMS
Product
October CMS
Classifications
CWE-862, T1059
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 3, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=1.0.471
  2. Affected versionversion=1.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

October CMS · October CMSversion=1.0.471; version=1.1.1

Published CVSS scores

5.2GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
5.2NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
4.4NIST NVDAV:L/AC:M/Au:N/C:P/I:P/A:P

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-862Missing Authorization
T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

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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