CVE-2021-44663Public exploitNetwork attack vector

Unauthenticated code execution via PHP upload validation bypass

Published Feb 24, 2022 · Updated Aug 4, 2024

Unrestricted file upload in Xerte Online Toolkits 3.8.4 and earlier allows remote attackers to execute code through elFinder. The elFinder connector tests uploaded content rather than reliably blocking PHP extensions, so leading characters before the PHP tag evade rejection. No authentication or user interaction is required, and successful exploitation runs an uploaded web shell under the web server account.

CVSS severity9.8
Critical
EPSS probability3.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Unrestricted file upload in Xerte Online Toolkits 3.8.4 and earlier allows remote attackers to execute code through elFinder. The elFinder connector tests uploaded content rather than reliably blocking PHP extensions, so leading characters before the PHP tag evade rejection. No authentication or user interaction is required, and successful exploitation runs an uploaded web shell under the web server account.

The record

CVE
CVE-2021-44663
Published
Feb 24, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1505.003, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 24, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1505.003Web Shell
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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