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Fencer Vulns
medium 5.8

CVE-2009-0777 json

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…

published 2009-03-05 17 y ago modified 2026-06-16 4 mo ago also EUVD-2009-0777

cvss
5.8
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

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.

Patch / fix

  • firefox RHEL 4 3.0.7-1.el4
  • firefox RHEL 5 3.0.7-1.el5
  • xulrunner RHEL 5 1.9.0.7-1.el5
  • xulrunner-devel-unstable RHEL 5 1.9.0.7-1.el5

red hat advisories RHSA-2009:0315

  • 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-2009-0777 updated cvss 4.3

Firefox URL spoofing with invisible control characters

  • Red Hat Enterprise Linux (v. 5 server) firefox 3.0.7-1.el5, xulrunner 1.9.0.7-1.el5, xulrunner-devel-unstable 1.9.0.7-1.el5 Red Hat Enterprise Linux AS version 4 firefox 3.0.7-1.el4 Red Hat Enterprise Linux Desktop (v. 5 client) firefox 3.0.7-1.el5, xulrunner 1.9.0.7-1.el5, xulrunner-devel-unstable 1.9.0.7-1.el5 Red Hat Enterprise Linux Desktop version 4 firefox 3.0.7-1.el4 Red Hat Enterprise Linux Desktop Workstation (v. 5 client) xulrunner 1.9.0.7-1.el5, xulrunner-devel-unstable 1.9.0.7-1.el5 Red Hat Enterprise Linux ES version 4 firefox 3.0.7-1.el4
    +1 more products
    Red Hat Enterprise Linux WS version 4 firefox 3.0.7-1.el4
    fixed: vendor fix RHSA-2009:0315

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

1.50% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:N/I:P/A:P

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns 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.