CVE-2021-41749: In the SEOmatic plugin up to 3.4.11 for Craft CMS 3, it is possible for unauthenticated attackers to perform a

Q: How do I fix CVE-2021-41749?

seomatic: upgrade to newer than 3.4.11. Exact commands for each OS are on this page.

Q: Is CVE-2021-41749 being exploited?

CVE-2021-41749 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-41749 affect?

CVE-2021-41749 affects seomatic. Severity is critical (CVSS 9.8). In the SEOmatic plugin up to 3.4.11 for Craft CMS 3, it is possible for unauthenticated attackers to perform a Server-Side Template Injection, allowing for remote code execution.

Q: How urgent is CVE-2021-41749?

Priority 64/100. Critical severity; EPSS top 3%: very likely to be exploited; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-41749 is a critical-severity flaw (CVSS 9.8) affecting seomatic. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the SEOmatic plugin up to 3.4.11 for Craft CMS 3, it is possible for unauthenticated attackers to perform a Server-Side Template Injection, allowing for remote code execution.

Why this priority

Critical severity
EPSS top 3%: very likely to be exploited
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	16.8% (top 3%)
CISA exploited list	No
Weakness	CWE-94
Published	2022-06-12
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: nystudio107

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

Am I affected?

Timeline

2022-06-12 11:15 UTCPublished CVE record published
2026-06-17 04:08 UTCUpdated Record last modified

nystudio107 seomatic UPGRADE

Affected: <= 3.4.11

Fixed in: newer than 3.4.11

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy seomatic || rpm -q seomatic || seomatic --version

2. UPGRADE to newer than 3.4.11 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade seomatic

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade seomatic

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Nuclei scan template: CraftCMS SEOmatic - Server-Side Template Injection

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-2021-41749?

seomatic: upgrade to newer than 3.4.11. Exact commands for each OS are on this page.

Is CVE-2021-41749 being exploited?

CVE-2021-41749 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-2021-41749 affect?

CVE-2021-41749 affects seomatic. Severity is critical (CVSS 9.8). In the SEOmatic plugin up to 3.4.11 for Craft CMS 3, it is possible for unauthenticated attackers to perform a Server-Side Template Injection, allowing for remote code execution.

How urgent is CVE-2021-41749?

Priority 64/100. Critical severity; EPSS top 3%: very likely to be exploited; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-44618 CRITICAL 9.8 DOWNGRADE A Server-side Template Injection (SSTI) vulnerability exists in Nystudio107 Seomatic 3.4.12 in src/helpers/Url
CVE-2021-41750 MEDIUM 6.1 DOWNGRADE A cross-site scripting (XSS) vulnerability in the SEOmatic plugin 3.4.10 for Craft CMS 3 allows remote attacke

References

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