JustSystems Ichitaro 2005 through 2011, Ichitaro Government 6, Ichitaro Government 2006 through 2010, Ichitaro Portable, Ichitaro Pro, and…

published 2011-07-18 15 y ago modified 2026-06-16 4 mo ago also EUVD-2011-1339

cvss: 9.3; version 2.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 5.6%; EPSS 5.6% chance of exploitation in 30 days, percentile 92%
public exploits: 0; none known

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.

Patch / fix

links 1

justsystems.com/jp/info/js11001.html advisory

Exploit prediction

5.56% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

symantec.com http://www.symantec.com/connect/blogs/targeted-attacks-2011-using-ichitaro-zero-day-vulnerability referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	2.0	9.3	AV:N/AC:M/Au:N/C:C/I:C/A:C

Classification

Weakness

CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

justsystems.com /jp/info/js11001.html
patch, vendor-advisory
symantec.com /connect/blogs/targeted-attacks-2011-using-ichitaro-zero-day-vulnerability
exploit
secunia.com /advisories/44956
third-party-advisory, vendor-advisory
securityfocus.com /bid/48283
vdb-entry
jvndb.jvn.jp /jvndb/JVNDB-2011-000043
third-party-advisory
exchange.xforce.ibmcloud.com /vulnerabilities/68072
vdb-entry
jvn.jp /en/jp/JVN87239473/index.html
third-party-advisory

Sources

CVE List CVE-2011-1331
NVD CVE-2011-1331

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary