CVE-2021-28121

CRITICALNVD 9.89.8—

9.8

Virtual Robots.txt before 1.10 does not block HTML tags in the robots.txt field.

CVSS v3: 9.8
EG Score: 9.8(medium)
EPSS: 77.1%
KEV: Not listed

Published

August 12, 2021

Last Modified

November 21, 2024

References (2)

cve@mitrehttps://wordpress.org/plugins/pc-robotstxt/#developers
af854a3a-2127-422b-91ae-364da2661108https://wordpress.org/plugins/pc-robotstxt/#developers

Data Freshness Timeline

(refreshed 12× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

2026-06-08 14:15 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 06:09 UTCEPSS rescore
2026-06-05 06:09 UTCEPSS rescore
2026-06-04 13:10 UTCEPSS rescore
2026-06-04 13:10 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 00:15 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-28121?

CVE-2021-28121 is a critical vulnerability published on August 12, 2021. Virtual Robots.txt before 1.10 does not block HTML tags in the robots.txt field.

When was CVE-2021-28121 disclosed?

CVE-2021-28121 was first published in the National Vulnerability Database on August 12, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-28121 actively exploited?

CVE-2021-28121 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 77.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-28121?

CVE-2021-28121 has a CVSS v3 base score of 9.8 (NVD).

How do I remediate CVE-2021-28121?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-28121, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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CVE-2021-28121

📅 Published

🔄 Last Modified

🔗 References (2)