CVE-2026-39878Public exploitNetwork attack vector

Administrator account takeover via stored registration XSS

Published Jul 20, 2026 · Updated Jul 20, 2026

Stored XSS in Chamilo LMS 1.11.38 and earlier allows remote attackers to run JavaScript in an administrator's browser through registration. main/auth/inscription.php accepts a null-byte payload that bypasses Security::remove_XSS(), while main/admin/user_list.php inserts the stored name into alt and title attributes without quote escaping. Self-registration must be enabled and an administrator must view the user list, after which the script can take over the administrator account and access or alter platform data.

CVSS severity9.3
Critical
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Chamilo LMS 1.11.38 and earlier allows remote attackers to run JavaScript in an administrator's browser through registration. main/auth/inscription.php accepts a null-byte payload that bypasses Security::remove_XSS(), while main/admin/user_list.php inserts the stored name into alt and title attributes without quote escaping. Self-registration must be enabled and an administrator must view the user list, after which the script can take over the administrator account and access or alter platform data.

The record

CVE
CVE-2026-39878
Published
Jul 20, 2026
Updated
Jul 20, 2026
Vendor
Chamilo
Product
Chamilo LMS
Classifications
CWE-79, T1136.001, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 1.11.38

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Chamilo · Chamilo LMSversion=<= 1.11.38

Published CVSS scores

9.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1136.001Create Account: Local Account
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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