Password disclosure via legacy SAMR RC4 encryption
Published Jul 14, 2021 · Updated Aug 10, 2026
An MS-SAMR security feature bypass in affected Microsoft Windows releases allows remote attackers to expose passwords in transit. Legacy SamrUnicodeChangePasswordUser2 and SamrSetInformationUser2 operations protect password buffers with RC4 rather than negotiated AES. Exploitation requires a password change or set operation and an attacker positioned to capture the traffic; the bounded impact is password disclosure.
Summary
What happened
An MS-SAMR security feature bypass in affected Microsoft Windows releases allows remote attackers to expose passwords in transit. Legacy SamrUnicodeChangePasswordUser2 and SamrSetInformationUser2 operations protect password buffers with RC4 rather than negotiated AES. Exploitation requires a password change or set operation and an attacker positioned to capture the traffic; the bounded impact is password disclosure.
The record
- CVE
- CVE-2021-33757
- Published
- Jul 14, 2021
- Updated
- Aug 10, 2026
- Vendor
- Microsoft
- Product
- Windows 10 Version 1507
- Classifications
- T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 14, 2021CVE publishedPublication date reported by the CVE source.
- Aug 10, 2026Record 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.
- Affected versionversion=10.0.10240.0 <10.0.10240.19003
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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