CVE-2021-41749Network attack vector

Unauthenticated code execution via poisoned forwarded host

Published Jun 12, 2022 · Updated Aug 4, 2024

Server-side template injection in nystudio107 SEOmatic 3.4.11 and earlier allows remote attackers to execute code via crafted HTTP headers. The safeCanonicalUrl method sanitizes a relative URL before UrlHelper adds an attacker-controlled X-Forwarded-Host value, leaving injected template syntax unsanitized. A deployment must trust and forward that header to Craft CMS; successful exploitation runs attacker-supplied code in the server process.

CVSS severity9.8
Critical
EPSS probability18.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side template injection in nystudio107 SEOmatic 3.4.11 and earlier allows remote attackers to execute code via crafted HTTP headers. The safeCanonicalUrl method sanitizes a relative URL before UrlHelper adds an attacker-controlled X-Forwarded-Host value, leaving injected template syntax unsanitized. A deployment must trust and forward that header to Craft CMS; successful exploitation runs attacker-supplied code in the server process.

The record

CVE
CVE-2021-41749
Published
Jun 12, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-94, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 12, 2022CVE 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/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
Privilegesunauthenticated
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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