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Fencer Intel
medium 5.4

CVE-2021-33851 json

A cross-site scripting (XSS) attack can cause arbitrary code (JavaScript) to run in a user's browser and can use an application as the vehi…

published 4y ago modified 4mo ago also EUVD-2021-20525

cvss
5.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 71%
public exploits
0
none known, plus a Nuclei check

Summary

A cross-site scripting (XSS) attack can cause arbitrary code (JavaScript) to run in a user's browser and can use an application as the vehicle for the attack. The XSS payload given in the "Custom logo link" executes whenever the user opens the Settings Page of the "Customize Login Image" Plugin.

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Exploit prediction

1.32% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • Nuclei template WordPress Customize Login Image <3.5.3 - Cross-Site Scripting nuclei detection template
  • cybersecurityworks.com https://cybersecurityworks.com/zerodays/cve-2021-33851-stored-cross-site-scripting-in-wordpress-customize-login-image.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 3.5 AV:N/AC:M/Au:S/C:N/I:P/A:N

Affected products

  • n/a WordPress Customize Login Image Plugin

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation
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.