CVE-2021-35413Public exploitNetwork attack vector

Authenticated code execution via uploaded .htaccess handler

Published Dec 3, 2021 · Updated Aug 4, 2024

Improper archive validation in Chamilo LMS 1.11.x allows remote authenticated users to execute arbitrary code through a crafted ZIP upload. The course_intro_pdf_import.php importer extracts attacker-controlled .htaccess and payload files into the web-accessible app/cache/pdfimport directory without disabling dangerous filenames. An authenticated account with access to the administrative importer is required; the .htaccess file assigns a PHP handler to the payload extension, enabling commands with web-server privileges.

CVSS severity8.8
High
EPSS probability2.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper archive validation in Chamilo LMS 1.11.x allows remote authenticated users to execute arbitrary code through a crafted ZIP upload. The course_intro_pdf_import.php importer extracts attacker-controlled .htaccess and payload files into the web-accessible app/cache/pdfimport directory without disabling dangerous filenames. An authenticated account with access to the administrative importer is required; the .htaccess file assigns a PHP handler to the payload extension, enabling commands with web-server privileges.

The record

CVE
CVE-2021-35413
Published
Dec 3, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-862, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 3, 2021CVE 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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.0NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:P

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-862Missing Authorization
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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