CVE-2009-1834: Mozilla Firefox

Medium severity, CVSS 4.3. EPSS: 3.2% chance of exploitation in the next 30 days.

Visual truncation vulnerability in netwerk/dns/src/nsIDNService.cpp in Mozilla Firefox before 3.0.11 and SeaMonkey before 1.1.17 allows remote attackers to spoof the location bar via an IDN with invalid Unicode characters that are displayed as whitespace, as demonstrated by the \u115A through \u115E characters.

Affected products

• Mozilla Firefox: up to and including 3.0.10; version 0.1 only; version 0.2 only; version 0.3 only; version 0.4 only; version 0.5 only; …
• Mozilla Seamonkey: up to and including 1.1.16; version 1.0 only; version 1.0.1 only; version 1.0.3 only; version 1.0.4 only; version 1.0.6 only; …

Published 2009-06-12. Last modified 2026-06-16.