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Fencer Intel
medium 6.8

CVE-2012-4203 json

The New Tab page in Mozilla Firefox before 17.0 uses a privileged context for execution of JavaScript code by bookmarklets, which allows us…

published 2012-11-21 13 y ago modified 2026-06-16 4 mo ago also EUVD-2012-4147

cvss
6.8
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.3%
EPSS 3.3% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

The New Tab page in Mozilla Firefox before 17.0 uses a privileged context for execution of JavaScript code by bookmarklets, which allows user-assisted remote attackers to run arbitrary programs by leveraging a javascript: URL in a bookmark.

Patch / fix

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 50.1.0-1.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10071-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2012-4203 updated cvss 4.3

Mozilla: Javascript: URLs run in privileged context on New Tab page (MFSA 2012-95)

  • Red Hat Enterprise Linux 5 firefox, thunderbird Red Hat Enterprise Linux 6 firefox, thunderbird
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.26% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-264 Permissions, Privileges, and Access Controls

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.