The compound that attacks pyrex glass is 

${\mathrm{XeF}}_6$ can be sublimed at room temperature it is more susceptible to hydrolysis $Xe{F}_6$ melt to give yellow liquid, since it attacks pyrex glass because silica react with $Xe{F}_6$.

$2{\mathrm{XeF}}_6+3{\mathrm{SiO}}_2\to 3{\mathrm{SiF}}_4+2{\mathrm{XeO}}_3$