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critical
CVE exact
CVE_2021_39863
What it means
PDF catalog uses a UTF-16BE /URI /Base value and JavaScript resolves a relative URL.
Why it fires
CVE-2021-39863 is an Adobe Acrobat/Reader heap-based buffer overflow in document base-URL concatenation. Exodus Intelligence documented that earlier research had associated this primitive with CVE-2021-21017, but Adobe assigned CVE-2021-39863 for the still-vulnerable bug. The rule requires the malformed UTF-16BE Base URL primitive plus submitForm(), app.launchURL(), or app.media.createPlayer() JavaScript, avoiding broad matches on ordinary PDF JavaScript or normal /URI actions.
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