JustSystems JUST Online Update, as used in Ichitaro through 2014 and other products, does not properly validate signatures of update modules, which allows remote attackers to spoof modules and execute arbitrary code via a crafted signature.

JustSystems Ichitaro 2005 through 2011, Ichitaro Government 6, Ichitaro Government 2006 through 2010, Ichitaro Portable, Ichitaro Pro, and Ichitaro Viewer allow remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via a crafted document, as exploited in the wild in early 2011.

Unspecified vulnerability in JustSystems Ichitaro 2004 through 2009, Ichitaro Government 2006 through 2009, and Just School 2008 and 2009 allows remote attackers to execute arbitrary code via unknown vectors related to "product character attribute processing" for a document.

Stack-based buffer overflow in JustSystems Corporation Ichitaro 13, 2004 through 2009, Viewer 2009 19.0.1.0 and earlier, and other versions allows context-dependent attackers to execute arbitrary code via a crafted Rich Text File (RTF), related to "pvpara ffooter."

Unspecified vulnerability in JustSystems Ichitaro 13, 2004 through 2008, Lite2, and Ichitaro viewer 5.1.5.0 and earlier allows remote attackers to execute arbitrary code via a crafted file, as exploited in the wild by Trojan.Tarodrop.H in March 2009.

Buffer overflow in JustSystems JSFC.DLL, as used in multiple JustSystems products such as Ichitaro, allows remote attackers to execute arbitrary code via a crafted .JTD file.

Stack-based buffer overflow in JSGCI.DLL in JustSystems Ichitaro 2005, 2006, and 2007 allows user-assisted remote attackers to execute arbitrary code via a crafted document, as actively exploited in December 2007 by the Tarodrop.F trojan. NOTE: some of these details are obtained from third party information.

Multiple buffer overflows in the rich text processing functionality in JustSystems Ichitaro 2004 through 2007, 11 through 13, and other versions allow remote attackers to execute arbitrary code via a long (1) pard field or (2) font name in the fcharset0 field, which is not properly handled in (a) JSTARO4.OCX; or (3) a long title, which is not properly handled by (b) TJSVDA.DLL.

Ichitaro 2005 through 2007, and possibly related products, allows remote attackers to have an unknown impact via unspecified vectors in a document distributed through e-mail or a web site, possibly due to a buffer overflow or cross-site scripting (XSS).

Buffer overflow in JustSystems Hanako 2004 through 2006, Hanako viewer 1.x, Ichitaro 2004, Ichitaro 2005, Ichitaro Lite2, Ichitaro viewer 4.x, and Sanshiro 2005 allows remote attackers to execute arbitrary code via the (1) Keyword and (2) Title fields, related to string length fields.