CVE-2021-37626Network attack vector

PHP file inclusion via insert tags

Published Aug 11, 2021 · Updated Aug 4, 2024

PHP file inclusion in affected Contao releases allows remote authenticated users to load arbitrary PHP files through back-end insert tags. The insert-tag processing path accepts a back-end-controlled PHP file reference and loads it without restricting the selected executable file. The flaw is reachable only when an untrusted back-end user can modify a field rendered in the front end, exposing data and permitting content changes in the web application's context.

CVSS severity5.4
Medium
EPSS probability1.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

PHP file inclusion in affected Contao releases allows remote authenticated users to load arbitrary PHP files through back-end insert tags. The insert-tag processing path accepts a back-end-controlled PHP file reference and loads it without restricting the selected executable file. The flaw is reachable only when an untrusted back-end user can modify a field rendered in the front end, exposing data and permitting content changes in the web application's context.

The record

CVE
CVE-2021-37626
Published
Aug 11, 2021
Updated
Aug 4, 2024
Vendor
Contao
Product
Contao
Classifications
CWE-94, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=>= 4.0.0, < 4.4.56
  2. Affected versionversion=>= 4.10.0, < 4.11.7
  3. Affected versionversion=>= 4.5.0, < 4.9.18

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Contao · Contaoversion=>= 4.0.0, < 4.4.56; version=>= 4.10.0, < 4.11.7; version=>= 4.5.0, < 4.9.18

Published CVSS scores

5.4GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
7.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1190Exploit Public-Facing Application

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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