CVE-2021-42583Network attack vector

Information exposure via weak password hash verification

Published Dec 28, 2021 · Updated Aug 4, 2024

Cryptographic weakness in Maddy before 0.5.2 allows remote attackers to expose sensitive information through password authentication. The shadow authentication verifier passes stored hashes to crypt.NewFromHash after registering APR1 and MD5-crypt, thereby accepting weak MD5-based password hashes. Exposure requires the shadow backend to contain such a hash; published sources do not identify the remotely observable data, limiting the established consequence to confidentiality loss.

CVSS severity7.5
High
EPSS probability0.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cryptographic weakness in Maddy before 0.5.2 allows remote attackers to expose sensitive information through password authentication. The shadow authentication verifier passes stored hashes to crypt.NewFromHash after registering APR1 and MD5-crypt, thereby accepting weak MD5-based password hashes. Exposure requires the shadow backend to contain such a hash; published sources do not identify the remotely observable data, limiting the established consequence to confidentiality loss.

The record

CVE
CVE-2021-42583
Published
Dec 28, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-327
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 28, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-327Use of a Broken or Risky Cryptographic Algorithm

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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