Which products and versions are affected by CVE-2009-0133?

Affected: Html Help Workshop (Microsoft) versions 4.74. The full list is in the CVE brief.

Is CVE-2009-0133 being exploited in the wild?

It is not listed in any known-exploited vulnerabilities catalog.

Is CVE-2009-0133 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2009-0133?

Public exploit code is available.

Is there a fix for CVE-2009-0133?

No fixed version is listed yet; check the vendor advisory for mitigations.

How urgently should CVE-2009-0133 be patched?

Brandefense priority: patch immediately, because it is very likely to be exploited soon.

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Vulnerability Intelligence

CVE-2009-0133

CriticalPublic exploit

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.

Published Jan 15, 2009 · Updated Apr 22, 2026

Key Facts

Patch immediately

CVE-2009-0133 is a critical-severity vulnerability (CVSS 10.0 v2) affecting Html Help Workshop (Microsoft).
It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
EPSS estimates a 67% probability of exploitation in the next 30 days.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.

CVSS v2

10.0

AV:N/AC:L/Au:N/C:C/I:C/A:C

EPSS (30-day exploit likelihood)

67%

Higher than 99.2% of all scored CVEs

Exploited in the wild

No known

Not in a known-exploited catalog

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2009-0133 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

Affected Products

1 affected entries in total

Product	Affected versions	Fixed in
Html Help WorkshopMicrosoft	4.74	n/a

Timeline

Publicly disclosed
Jan 15, 2009
Last updated
Apr 22, 2026

Weakness Type

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

References

4 more references in the full CVE brief

FAQ

Common Questions.

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.
Affected: Html Help Workshop (Microsoft) versions 4.74. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.

Is CVE-2009-0133 Running On Your Attack Surface?

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