CVE-2021-28998

HIGHNVD 7.27.2—Elevated

7.2

File upload vulnerability in CMS Made Simple through 2.2.15 allows remote authenticated attackers to gain a webshell via a crafted phar file.

CVSS v3: 7.2
EG Score: 7.2(medium)
EPSS: 75.0%
KEV: Not listed

Published

May 8, 2023

Last Modified

January 29, 2025

References (4)

cve@mitrehttps://github.com/beerpwn/CVE/blob/master/cms_made_simple_2021/file_upload_RCE/File_upload_to_RCE.md
cve@mitrehttps://seclists.org/fulldisclosure/2021/Mar/50
af854a3a-2127-422b-91ae-364da2661108https://github.com/beerpwn/CVE/blob/master/cms_made_simple_2021/file_upload_RCE/File_upload_to_RCE.md
af854a3a-2127-422b-91ae-364da2661108https://seclists.org/fulldisclosure/2021/Mar/50

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-434Unrestricted Upload of File with Dangerous Type

Data Freshness Timeline

(refreshed 9× in last 7d / 18× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-04 13:10 UTCepss_batch
2026-06-04 13:10 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-25 01:50 UTCEG score recompute
2026-05-25 01:50 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-28998?

CVE-2021-28998 is a high vulnerability published on May 8, 2023. File upload vulnerability in CMS Made Simple through 2.2.15 allows remote authenticated attackers to gain a webshell via a crafted phar file.

When was CVE-2021-28998 disclosed?

CVE-2021-28998 was first published in the National Vulnerability Database on May 8, 2023, with the most recent update on January 29, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-28998 actively exploited?

CVE-2021-28998 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 75.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-28998?

CVE-2021-28998 has a CVSS v3 base score of 7.2 (NVD).

How do I remediate CVE-2021-28998?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-28998, 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-2021-28998

📅 Published

🔄 Last Modified

🔗 References (4)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-28998?

🔗 Related CVEs(same CWE)

Same CWE

Published

Last Modified

References (4)

Frequently asked(5)

Related CVEs(same CWE)