CVE-2026-1238: SlimStat Analytics <= 5.3.5 - Unauthenticated Stored Cross-Site Scripting via 'fh'

Severity: high (CVSS 7.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-19 · updated 2026-06-17
Weakness: CWE-79

Description

The SlimStat Analytics plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'fh' (fingerprint) parameter in all versions up to, and including, 5.3.5 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Affected products

veronalabs SlimStat Analytics: through 5.3.5

References

https://plugins.trac.wordpress.org/browser/wp-slimstat/tags/5.3.5/admin/view/right-now.php#L185
https://plugins.trac.wordpress.org/browser/wp-slimstat/tags/5.3.5/wp-slimstat.php#L1948
https://plugins.trac.wordpress.org/changeset/3477417/
https://www.wordfence.com/threat-intel/vulnerabilities/id/e991fbdf-8e26-4d2e-8e3b-c8990914dcad?source=cve

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