\fonttbl heap overflow — CVE-2023-21716

CVE_2023_21716

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critical CVE exact CVE_2023_21716

What it means

RTF font table with excessive entries — Word heap buffer overflow.

Why it fires

CVE-2023-21716 is a critical heap buffer overflow in Microsoft Word's RTF parser triggered by an RTF file with an abnormally large number of font entries in the \fonttbl group. The rule requires a \fonttbl and counts at least 32768 \fN font entries, matching the public exploit-scale trigger rather than merely large but valid font tables.

Other CVE heuristics

CVE_2026_34621_RELATED CVE_2023_26369 CVE_2026_34621 CVE_2010_1297_FLASH_RICHMEDIA CVE_2010_1297_SWF_TRIGGER CVE_2011_0611_SWF_TRIGGER CVE_2009_1862_FLASH_RICHMEDIA CVE_2010_2883 CVE_2018_4901 CVE_2009_3459 CVE_2018_4990_JPX_EMBEDDED_CMD CVE_2018_4990_JPX_CMAP_TRIGGER CVE_2010_1240 CVE_2010_0188 CVE_2014_0514 CVE_2013_3346 CVE_2013_0640 CVE_2010_3654_FLASH_RICHMEDIA CVE_2007_5020_MAILTO_MSHTA CVE_2014_0496 CVE_2008_2551 CVE_2021_40444 CVE_2006_4694 CVE_2008_0118