CVE-2021-4403: The Remove Schema plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and incl

Q: How do I fix CVE-2021-4403?

remove schema: upgrade to newer than 1.5. Exact commands for each OS are on this page.

Q: Is CVE-2021-4403 being exploited?

CVE-2021-4403 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-4403 affect?

CVE-2021-4403 affects remove schema. Severity is medium (CVSS 4.3). The Remove Schema plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.5. This is due to missing or incorrect nonce validation on the validate() function. This makes it possible for unauthenti

Q: How urgent is CVE-2021-4403?

Priority 23/100. No elevated risk signals yet.

Routine

MEDIUM 4.3UPGRADE

CVE-2021-4403 is a medium-severity flaw (CVSS 4.3) affecting remove schema. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Remove Schema plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.5. This is due to missing or incorrect nonce validation on the validate() function. This makes it possible for unauthenticated attackers to modify the plugins settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-352
Published	2023-07-01
Last modified	2026-06-17

Publisher (CNA): Wordfence · Vendor: websitescanner

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-07-01 06:15 UTCPublished CVE record published
2026-06-17 04:19 UTCUpdated Record last modified

websitescanner remove schema UPGRADE

Affected: <= 1.5

Fixed in: newer than 1.5

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy remove-schema || rpm -q remove-schema || remove-schema --version

2. UPGRADE to newer than 1.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade remove-schema

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade remove-schema

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-4403?

remove schema: upgrade to newer than 1.5. Exact commands for each OS are on this page.

Is CVE-2021-4403 being exploited?

CVE-2021-4403 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-4403 affect?

CVE-2021-4403 affects remove schema. Severity is medium (CVSS 4.3). The Remove Schema plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.5. This is due to missing or incorrect nonce validation on the validate() function. This makes it possible for unauthenti

How urgent is CVE-2021-4403?

Priority 23/100. No elevated risk signals yet.

Software pages

WordPress vulnerabilities

References

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