How severe is CVE-2025-5821?

CVE-2025-5821 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-5821 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-5821?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2025-5821 have an EU (EUVD) identifier?

Yes. CVE-2025-5821 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-25634.

When was CVE-2025-5821 published?

CVE-2025-5821 was published on 2025-08-23 and last updated on 2026-06-17.

CVE-2025-5821

CVE-2025-5821 is a critical-severity vulnerability with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-288.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (49th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-25634
Weakness: CWE-288
Published: 2025-08-23
Last modified: 2026-06-17

Description

The Case Theme User plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 1.0.3. This is due to the plugin not properly logging in a user with the data that was previously verified through the facebook_ajax_login_callback() function. This makes it possible for unauthenticated attackers to log in as administrative users, as long as they have an existing account on the site which can easily be created by default through the temp user functionality, and access to the administrative user's email.

Frequently asked questions

What is CVE-2025-5821?: The Case Theme User plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 1.0.3. This is due to the plugin not properly logging in a user with the data that was previously verified through the facebook_ajax_login_callback() function. This makes it possible for unauthenticated attackers to log in as administrative users, as long as they have an existing account on the site which can easily be created by default through the temp user functionality, and access to the administrative user's email.
How severe is CVE-2025-5821?: CVE-2025-5821 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-5821 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-5821?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2025-5821 have an EU (EUVD) identifier?: Yes. CVE-2025-5821 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-25634.
When was CVE-2025-5821 published?: CVE-2025-5821 was published on 2025-08-23 and last updated on 2026-06-17.

References

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