CVE-2021-41836: The Fathom Analytics WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input v

Q: How do I fix CVE-2021-41836?

fathom analytics: upgrade to newer than 3.0.4. Exact commands for each OS are on this page.

Q: Is CVE-2021-41836 being exploited?

CVE-2021-41836 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-2021-41836 affect?

CVE-2021-41836 affects fathom analytics. Severity is medium (CVSS 4.8). The Fathom Analytics WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and escaping via the $site_id parameter found in the ~/fathom-analytics.php file which allowed attackers with administra

Q: How urgent is CVE-2021-41836?

Priority 29/100. No elevated risk signals yet.

Routine

MEDIUM 4.8UPGRADE

CVE-2021-41836 is a medium-severity flaw (CVSS 4.8) affecting fathom analytics. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Fathom Analytics WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and escaping via the $site_id parameter found in the ~/fathom-analytics.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 3.0.4. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_ht

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.8 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	Required
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-12-14
Last modified	2026-06-17

Publisher (CNA): Wordfence · Vendor: conva

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

Am I affected?

Timeline

2021-12-14 16:15 UTCPublished CVE record published
2026-06-17 04:08 UTCUpdated Record last modified

conva fathom analytics UPGRADE

Affected: <= 3.0.4

Fixed in: newer than 3.0.4

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy fathom-analytics || rpm -q fathom-analytics || fathom-analytics --version

2. UPGRADE to newer than 3.0.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade fathom-analytics

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fathom-analytics

Note

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

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-2021-41836?

fathom analytics: upgrade to newer than 3.0.4. Exact commands for each OS are on this page.

Is CVE-2021-41836 being exploited?

CVE-2021-41836 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-2021-41836 affect?

CVE-2021-41836 affects fathom analytics. Severity is medium (CVSS 4.8). The Fathom Analytics WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and escaping via the $site_id parameter found in the ~/fathom-analytics.php file which allowed attackers with administra

How urgent is CVE-2021-41836?

Priority 29/100. No elevated risk signals yet.

Software pages

WordPress vulnerabilities · PHP vulnerabilities

References

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