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Fencer Intel
critical 9.8

CVE-2021-4073 json

RegistrationMagic <= 5.0.1.7 Authentication Bypass

published 4y ago modified 4mo ago also EUVD-2021-33966

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
6.8%
EPSS 6.8% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known, plus a Nuclei check

Summary

The RegistrationMagic WordPress plugin made it possible for unauthenticated users to log in as any site user, including administrators, if they knew a valid username on the site due to missing identity validation in the social login function social_login_using_email() of the plugin. This affects versions equal to, and less than, 5.0.1.7.

Patch / fix

Is CVE-2021-4073 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
last yr.

Exploit prediction

6.84% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • Nuclei template RegistrationMagic <= 5.0.1.7 - Authentication Bypass nuclei detection template
  • wordfence.com https://www.wordfence.com/blog/2021/12/authentication-bypass-vulnerability-patched-in-user-registration-plugin/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • RegistrationMagic RegistrationMagic

Classification

Weakness
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.