This indicates an attack attempt to exploit a memory-corruption vulnerability in Mozilla.
This vulnerability is caused by an error when the vulnerable software is parsing an XLS file that includes a malicious "xsl:key" elment. It allows a remote attacker to crash the vulnerable software via sending a crafted XLS file.
Mozilla Firefox before 3.0.8
Mozilla SeaMonkey before 1.1.16
System Compromise: Remote attackers can crash vulnerable systems.
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