SzafirHost verifies the signature of the downloaded JAR file using class JarInputStream (reading from the beginning of the file), but loads classes using class JarFile/URLClassLoader (reading the Central Directory from the end). It can lead to remote code execution by allowing an attacker to combine a genuine, signed JAR file with a malicious ZIP file, causing the verification to pass but the malicious class to be loaded.
This issue was fixed in version 1.2.1.
Exploitability
AV:NAC:LAT:NPR:NUI:AVulnerable System
VC:HVI:HVA:HSubsequent System
SC:LSI:LSA:L8.6/CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:L/SI:L/SA:LOther