How severe is CVE-2011-3866?

CVE-2011-3866 has a CVSS 2.0 base score of 4.3, rated medium severity.

Is CVE-2011-3866 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-3866?

CVE-2011-3866 primarily affects Mozilla Firefox. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2011-3866?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2011-3866 published?

CVE-2011-3866 was published on 2011-09-29 and last updated on 2026-06-16.

CVE-2011-3866

CVE-2011-3866 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 4.3. 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-264.

Key facts

Severity: Medium (CVSS 2.0 base score 4.3)
EPSS exploit prediction: 1% (69th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-264
Affected product: Mozilla Firefox
Published: 2011-09-29
Last modified: 2026-06-16

Description

Mozilla Firefox before 7.0 and SeaMonkey before 2.4 do not properly restrict availability of motion data events, which makes it easier for remote attackers to read keystrokes by leveraging JavaScript code running in a background tab.

Frequently asked questions

What is CVE-2011-3866?: Mozilla Firefox before 7.0 and SeaMonkey before 2.4 do not properly restrict availability of motion data events, which makes it easier for remote attackers to read keystrokes by leveraging JavaScript code running in a background tab.
How severe is CVE-2011-3866?: CVE-2011-3866 has a CVSS 2.0 base score of 4.3, rated medium severity.
Is CVE-2011-3866 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2011-3866?: CVE-2011-3866 primarily affects Mozilla Firefox. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2011-3866?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2011-3866 published?: CVE-2011-3866 was published on 2011-09-29 and last updated on 2026-06-16.

References

Affected products (2)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:seamonkey:*:*:*:*:*:*:*:*

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