How severe is CVE-2021-47904?

CVE-2021-47904 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-47904 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2021-47904?

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

Does CVE-2021-47904 have an EU (EUVD) identifier?

Yes. CVE-2021-47904 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-4274.

When was CVE-2021-47904 published?

CVE-2021-47904 was published on 2026-01-23 and last updated on 2026-06-17.

CVE-2021-47904

CVE-2021-47904 is a high-severity vulnerability with a CVSS 3.x base score of 8.8. 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-434.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v4: 8.7
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-4274
Weakness: CWE-434
Published: 2026-01-23
Last modified: 2026-06-17

Description

PhreeBooks 5.2.3 contains an authenticated file upload vulnerability in the Image Manager that allows remote code execution. Attackers can upload a malicious PHP web shell by exploiting unrestricted file type uploads to gain command execution on the server.

Frequently asked questions

What is CVE-2021-47904?: PhreeBooks 5.2.3 contains an authenticated file upload vulnerability in the Image Manager that allows remote code execution. Attackers can upload a malicious PHP web shell by exploiting unrestricted file type uploads to gain command execution on the server.
How severe is CVE-2021-47904?: CVE-2021-47904 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-47904 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2021-47904?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2021-47904 have an EU (EUVD) identifier?: Yes. CVE-2021-47904 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-4274.
When was CVE-2021-47904 published?: CVE-2021-47904 was published on 2026-01-23 and last updated on 2026-06-17.

References

Other CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities

CVE-2026-48283 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Unrestricted Upload of File with Dangerous Type…
CVE-2026-48276 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Unrestricted Upload of File with Dangerous Type…
CVE-2026-57700 — Critical (CVSS 10.0): Unrestricted Upload of File with Dangerous Type vulnerability in Daan.Dev OMGF Pro allows Using Malicious Files. This…
CVE-2025-69129 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in WordPress & WooCommerce Scraper Plugin, Import Data from Any Site <= 1.0.7…
CVE-2026-40772 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in GeekyBot <= 1.2.2 versions.
CVE-2026-40412 — Critical (CVSS 10.0): Unrestricted upload of file with dangerous type in Azure Orbital Spatio allows an unauthorized attacker to execute code…

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