CVE-2005-0255: Mozilla Firefox

Medium severity, CVSS 5.0. EPSS: 4.3% chance of exploitation in the next 30 days.

String handling functions in Mozilla 1.7.3, Firefox 1.0, and Thunderbird before 1.0.2, such as the nsTSubstring_CharT::Replace function, do not properly check the return values of other functions that resize the string, which allows remote attackers to cause a denial of service and possibly execute arbitrary code by forcing an out-of-memory state that causes a reallocation to fail and return a pointer to a fixed address, which leads to heap corruption.

Affected products

• Mozilla Firefox: version 1.0 only
• Mozilla Mozilla: version 1.7.3 only
• Mozilla Thunderbird: version 0.1 only; version 0.2 only; version 0.3 only; version 0.4 only; version 0.5 only; version 0.6 only; …

Published 2005-05-02. Last modified 2026-06-16.