Is CVE-2006-6503 in the CISA KEV catalog?

No. CVE-2006-6503 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2006-6503?

CVE-2006-6503 has a CVSS v2 base score of 6.8 (MEDIUM).

What is the EPSS score for CVE-2006-6503?

CVE-2006-6503 has an EPSS score of 3.97% (89th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2006-6503?

Upgrade firefox on debian unstable to 45.0-1 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2006-6503

MEDIUMEPSS 89th pctl

6.8

CVSS v2

NVD

Description

Mozilla Firefox 2.x before 2.0.0.1, 1.5.x before 1.5.0.9, Thunderbird before 1.5.0.9, and SeaMonkey before 1.0.7 allows remote attackers to bypass cross-site scripting (XSS) protection by changing the src attribute of an IMG element to a javascript: URI.

CWE-254

How to fix

Remediation Available

firefoxDebian

Fixed in:45.0-1CVE-2006-6503

DeveloperEditionWindows application

Affected:2.0 2.0.0.1Fixed in:2.0.0.1Mozilla

Affected:1.5 1.5.0.9Fixed in:1.5.0.9Mozilla

Mozilla Firefox (en-US)Windows application

Affected:2.0 2.0.0.1Fixed in:2.0.0.1Mozilla

Affected:1.5 1.5.0.9Fixed in:1.5.0.9Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:1.5.0.9Fixed in:1.5.0.9Mozilla

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v2 Vector

No CVSS vector data available.

Exploit Intelligence

3.97%probability of exploitation in 30 days

89thpercentile

Elevated risk: more likely to be exploited than 89% of all known CVEs.

References

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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.