The Javascript interpreter (jsinterp.c) in Mozilla and Firefox before 1.5.1 does not properly dereference objects, which allows remote attackers to cause a denial of service (crash) or execute arbitrary code via unknown attack vectors related to garbage collection.
Exploitability
AV:NAC:LAu:NImpact
C:PI:PA:P7.5/AV:N/AC:L/Au:N/C:P/I:P/A:P