CVE-2009-4171

Messenger vulnerability

CVSS

4.3

EPSS

5.1%

EPSS pct

91th

Exploited

No known

An ActiveX control in YahooBridgeLib.dll for Yahoo! Messenger 9.0.0.2162, and possibly other 9.0 versions, allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) by calling the RegisterMe method with a long argument.

Affected vendor

Yahoo

Affected product

Messenger

CVSS vector

AV:N/AC:M/Au:N/C:N/I:N/A:P

Weakness type (CWE)

CWE-119 — Improper Restriction of Operations within Memory Bounds

Published

2009-12-02

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, medium attack complexity, requiring no authentication. Successful exploitation leads to partial impact to availability.

Its EPSS score of 5.1% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 91% of all scored CVEs.

Check your external exposure to CVE-2009-4171

Confirm whether Yahoo Messenger is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2009-4171.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2009-4171

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2009-4171 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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