What is CVE-2009-0133?

CVE-2009-0133 is a vulnerability in Microsoft HTML Help Workshop, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. Published 2009-01-15.

Is CVE-2009-0133 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Microsoft HTML Help Workshop

CVE-2009-0133

Buffer overflow in Microsoft HTML Help Workshop 4.74 and earlier allows context-dependent attackers to execute arbitrary code via a .hhp file with a long "Index file" field, possibly a related issue to CVE-2006-0564.

Vulnerability class: Buffer Overflow

Published 2009-01-15 · last modified 2026-06-16.

CVSS v2 metric

CVSS v2 base score 10.0 (High). Vector: AV:N/AC:L/Au:N/C:C/I:C/A:C. This CVE predates CVSS v3 and has no v3 score from NVD.

EPSS exploit prediction

EPSS: 0.670 (99.3th percentile), scored 2026-10-19.

High probability of exploitation in the next 30 days — patch promptly. 99th percentile — 99.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.670 · newest: 0.670 · change: 0.000

Affected products

Microsoft HTML Help Workshop — versions 4.74

Weakness classification (CWE)

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

Public proof-of-concept exploits

rapid7/metasploit-framework

References

www.exploit-db.com/exploits/7727 (exploit)
securityreason.com/securityalert/4914 (third-party-advisory)

Frequently asked questions

What is CVE-2009-0133?: CVE-2009-0133 is a vulnerability in Microsoft HTML Help Workshop, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. Published 2009-01-15.
Is CVE-2009-0133 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.