CVE-2006-6503

CVE-2006-6503 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 6.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-254.

Key facts

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.

Frequently asked questions

What is CVE-2006-6503?
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.
How severe is CVE-2006-6503?
CVE-2006-6503 has a CVSS 2.0 base score of 6.8, rated medium severity.
Is CVE-2006-6503 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2006-6503?
CVE-2006-6503 primarily affects Mozilla Firefox. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2006-6503?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2006-6503 published?
CVE-2006-6503 was published on 2006-12-20 and last updated on 2026-06-16.

References

Affected products (8)

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