Firefox 2.0.0.18 contains updates for 11 flaws -- six labeled critical, while Firefox 3.0.4 closes nine flaws -- four deemed critical.
The vulnerabilities could be exploited to execute a range of attacks, including arbitrary code injection, privilege escalation, cross-site scripting, denial-of-service, security bypass and information disclosure, according to a US-CERT alert.
Also on Wednesday, Mozilla released a new version of its open-source internet suite, SeaMonkey, which comes outfitted with the same fixes as Firefox 2.0.0.18.
Users are advised to upgrade to Firefox 3, as Mozilla plans to cut support for Firefox 2 around mid-December.