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Fencer Vulns
medium 5.5

CVE-2021-39356 json

Content Staging <= 2.0.1 Authenticated Stored Cross-Site Scripting

published 2021-10-21 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-25717

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 62%
public exploits
0
none known

Summary

The Content Staging WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and escaping via several parameters that are echo'd out via the ~/templates/settings.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 2.0.1. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
20 mo ago

Exploit prediction

0.99% chance of exploitation in the next 30 days, higher than 62% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/BigTiger2020/word-press/blob/main/Content%20Staging.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.5 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
NVD 3.1 4.8 CVSS:3.1/AV:N/AC:L/PR:H/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

  • Content Staging Content Staging

Classification

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

References

Sources

Fencer Vulns 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.