The flaws could put users at risk of security bypass, manipulation of data and denial-of-service attacks, according to an advisory from research outfit Secunia, which rates the vulnerabilities as "highly critical."
Symantec confirmed that the vulnerabilities had been identified in the Symantec Firewall/VPN Appliance 100, 200 and 200R models. The Symantec Gateway Security 320, 360 and 360R are vulnerable to only two of the issues, which have been resolved, the company explained in a note posted online.
"All of these vulnerabilities are remotely exploitable and can allow an attacker to perform a denial of service attack against the firewall appliance, identify active services in the WAN interface, and exploit one of these services to collect and alter the firewalls configuration," the company warned.
The security holes, discovered by Rigel Kent Security & Advisory Services, also affect the Nexland ISB SOHO, Pro100, Pro400, Pro800, Pro800turbo and the Nexland WaveBase Firewall Appliances.
The Symantec Gateway Security models 320, 360 and 360R are not vulnerable to the denial-of-service issue but have been validated as being vulnerable to the other two issues.
Symantec is urging customers to upgrade to the firmware builds labeled 1.63 for Symantec Firewall/VPN Appliance models100, 200 and 200R. Firmware build 622 has been posted for the Symantec Gateway Security Appliance models 320, 360 and 360R.
The company has also released firmware build 16U for the Nexland Firewall Appliances.
The Nexland firewall appliances, which Symantec acquired last year, are primarily used in branch offices and home offices.