CVE-2021-4399 | Edwiser Bridge <= 2.0.6 - Cross-Site Request Forgery Bypass

The Edwiser Bridge plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including,2.0.6. This is due to missing or incorrect nonce validation on the user_data_synchronization_initiater(), course_synchronization_initiater(), users_link_to_moodle_synchronization(), connection_test_initiater(), admin_menus(), and subscribe_handler() function. This makes it possible for unauthenticated attackers to perform unauthorized actions via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

Published: 2023-07-01 Last update: 2026-04-08 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-4399 is rated Low Risk (27.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.37%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-4399

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.15% 0.37% +0.22%
2 2026-04-21 0.12% 0.15% +0.03%
3 2025-11-21 — 0.12% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-4399

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]

Weakness enumeration for CVE-2021-4399

Affected software / configurations for CVE-2021-4399

Vendor Product Version Raw CPE
edwiser bridge <= 2.0.6 cpe:2.3:a:edwiser:bridge:*:*:*:*:*:wordpress:*:*

References for CVE-2021-4399

URL Tags
https://blog.nintechnet.com/25-wordpress-plugins-vulnerable-to-csrf-attacks/ Not Applicable
https://blog.nintechnet.com/more-wordpress-plugins-and-themes-vulnerable-to-csrf-attacks/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-1/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-2/ Third Party Advisory
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-3/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-4/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-5/ Not Applicable
https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=2478642%40edwiser-bridge&new=2478642%40edwiser-bridge&sfp_email=&sfph_mail= Patch
https://www.wordfence.com/threat-intel/vulnerabilities/id/6450dafd-5992-4831-87af-e5e47cc8663e?source=cve Third Party Advisory
cvelogic Threat Intelligence