How severe is CVE-2009-3012?

CVE-2009-3012 has a CVSS 2.0 base score of 4.3, rated medium severity.

Is CVE-2009-3012 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-3012?

CVE-2009-3012 primarily affects Mozilla Firefox. In total, 20 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-3012?

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

When was CVE-2009-3012 published?

CVE-2009-3012 was published on 2009-08-31 and last updated on 2026-06-16.

CVE-2009-3012

CVE-2009-3012 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-79.

Key facts

Severity: Medium (CVSS 2.0 base score 4.3)
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Mozilla Firefox
Published: 2009-08-31
Last modified: 2026-06-16

Description

Mozilla Firefox 3.0.13 and earlier, 3.5, 3.6 a1 pre, and 3.7 a1 pre does not properly block data: URIs in Location headers in HTTP responses, which allows remote attackers to conduct cross-site scripting (XSS) attacks via vectors related to (1) injecting a Location header that contains JavaScript sequences in a data:text/html URI or (2) entering a data:text/html URI with JavaScript sequences when specifying the content of a Location header. NOTE: the JavaScript executes outside of the context of the HTTP site.

Frequently asked questions

What is CVE-2009-3012?: Mozilla Firefox 3.0.13 and earlier, 3.5, 3.6 a1 pre, and 3.7 a1 pre does not properly block data: URIs in Location headers in HTTP responses, which allows remote attackers to conduct cross-site scripting (XSS) attacks via vectors related to (1) injecting a Location header that contains JavaScript sequences in a data:text/html URI or (2) entering a data:text/html URI with JavaScript sequences when specifying the content of a Location header. NOTE: the JavaScript executes outside of the context of the HTTP site.
How severe is CVE-2009-3012?: CVE-2009-3012 has a CVSS 2.0 base score of 4.3, rated medium severity.
Is CVE-2009-3012 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-3012?: CVE-2009-3012 primarily affects Mozilla Firefox. In total, 20 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-3012?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2009-3012 published?: CVE-2009-3012 was published on 2009-08-31 and last updated on 2026-06-16.

References

Affected products (20)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0:alpha:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0:beta2:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0:beta5:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.1:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.2:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.3:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.4:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.5:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.6:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.7:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.8:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.9:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.10:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.11:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.0.12:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.5:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.6:a1_pre:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:3.7:a1_pre:*:*:*:*:*:*

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