CVE-2009-0777

CVE-2009-0777 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 5.8. 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-20.

Key facts

Description

Mozilla Firefox before 3.0.7, Thunderbird before 2.0.0.21, and SeaMonkey before 1.1.15 decode invisible characters when they are displayed in the location bar, which causes an incorrect address to be displayed and makes it easier for remote attackers to spoof URLs and conduct phishing attacks.

Frequently asked questions

What is CVE-2009-0777?
Mozilla Firefox before 3.0.7, Thunderbird before 2.0.0.21, and SeaMonkey before 1.1.15 decode invisible characters when they are displayed in the location bar, which causes an incorrect address to be displayed and makes it easier for remote attackers to spoof URLs and conduct phishing attacks.
How severe is CVE-2009-0777?
CVE-2009-0777 has a CVSS 2.0 base score of 5.8, rated medium severity.
Is CVE-2009-0777 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-0777?
CVE-2009-0777 primarily affects Mozilla Firefox. In total, 88 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-0777?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2009-0777 published?
CVE-2009-0777 was published on 2009-03-05 and last updated on 2026-06-16.

References

Affected products (88)

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