CVE-2021-43844Network attack vector

Remote code execution via accepted local file URL

Published Dec 20, 2021 · Updated Aug 4, 2024

Remote code execution in Robert Maehl Software MSEdgeRedirect before 0.5.0.1 allows remote attackers to launch a file via a crafted URL. The _DecodeAndRun() function treats file:/// input as a web resource because its _WinAPI_UrlIs() check accepts local file URLs, then launches the resolved file. Exploitation requires a user to visit an attacker-controlled page, download a payload, accept the crafted URL prompt, and have its path guessed.

CVSS severity8.8
High
EPSS probability3.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in Robert Maehl Software MSEdgeRedirect before 0.5.0.1 allows remote attackers to launch a file via a crafted URL. The _DecodeAndRun() function treats file:/// input as a web resource because its _WinAPI_UrlIs() check accepts local file URLs, then launches the resolved file. Exploitation requires a user to visit an attacker-controlled page, download a payload, accept the crafted URL prompt, and have its path guessed.

The record

CVE
CVE-2021-43844
Published
Dec 20, 2021
Updated
Aug 4, 2024
Vendor
Robert Maehl Software
Product
MSEdgeRedirect
Classifications
CWE-610, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.5.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Robert Maehl Software · MSEdgeRedirectversion=< 0.5.0.1

Published CVSS scores

8.8GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-610Externally Controlled Reference to a Resource in Another Sphere
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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