Is CVE-2006-6421 in the CISA KEV catalog?

No. CVE-2006-6421 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2006-6421?

CVE-2006-6421 has a CVSS v2 base score of 6.0 (MEDIUM).

What is the EPSS score for CVE-2006-6421?

CVE-2006-6421 has an EPSS score of 15.00% (96th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2006-6421

MEDIUMEPSS 96th pctl

6.0

CVSS v2

NVD

Description

Cross-site scripting (XSS) vulnerability in the private message box implementation (privmsg.php) in phpBB 2.0.x allows remote authenticated users to inject arbitrary web script or HTML via the "Message body" field in a message to a non-existent user.

CVSS v2 Vector

No CVSS vector data available.

Exploit Intelligence

15.00%probability of exploitation in 30 days

96thpercentile

Very high risk: more likely to be exploited than 96% of all known CVEs.

References

http://secunia.com/advisories/23283
http://securityreason.com/securityalert/2005
http://www.phpbb.com/phpBB/viewtopic.php?f=14&t=489624
http://www.securityfocus.com/archive/1/453774/100/0/threaded
http://www.securityfocus.com/archive/1/456579/100/0/threaded
http://www.securityfocus.com/archive/1/456728/100/100/threaded
http://www.securityfocus.com/archive/1/456784/100/100/threaded
http://www.securityfocus.com/bid/21806
http://www.securityfocus.com/bid/22001
https://exchange.xforce.ibmcloud.com/vulnerabilities/30776

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-23.