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CVE-2012-3989

29
FAUCET Score

CVE-2012-3989 is a critical vulnerability affecting Mozilla Firefox, Thunderbird, and SeaMonkey versions prior to 16.0/2.13, stemming from improper variable casting during JavaScript instanceof operations. With a CVSS score of 9.3, it allows remote attackers to achieve arbitrary code execution or denial of service via a crafted website, requiring medium attack complexity but no authentication. While there is no known active exploitation, public exploit code, or KEV listing, the vulnerability has garnered significant community discussion, indicating awareness despite its age.

Impacted Technologies

VendorProductVersion(s)CPE
< 16.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 2.13CPE matchmatch criteria
cpe:2.3:a:mozilla:seamonkey:*:*:*:*:*:*:*:*
< 16.0CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
10.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:10.04:*:*:*:*:*:*:*
11.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:11.04:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

9.3HIGH

AV:N/AC:M/Au:N/C:C/I:C/A:C

Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Exploitability Score
8.6
Impact Score
10.0
CvssVersion
2.0

Exploit Intelligence

EPSS Score
3.46%
Probability of exploitation in next 30 days
EPSS Percentile
87.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0346 is in the 47th percentile among its peer group of 8,914 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2012-3989Critical

Mozilla: Crash with invalid cast when using instanceof operator (MFSA 2012-80)

Oct 9, 2012

References

lists.opensuse.org / opensuse-security-announce/2012-10/msg00010.html
Mailing ListThird Party Advisory
osvdb.org / 86097
Broken Link
bugzilla.mozilla.org / show_bug.cgi
Issue TrackingVendor Advisory
secunia.com / advisories/50856
Broken Link
secunia.com / advisories/50892
Broken Link
secunia.com / advisories/50904
Broken Link
secunia.com / advisories/50935
Broken Link
secunia.com / advisories/50984
Broken Link
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16814
Third Party Advisory
mozilla.org / security/announce/2012/mfsa2012-80.html
Vendor Advisory
ubuntu.com / usn/USN-1611-1
Third Party Advisory