CVE-2026-31940Network attack vector

Account takeover via attacker-chosen session identifiers

Published Apr 10, 2026 · Updated Apr 10, 2026

Session fixation in Chamilo LMS before 1.11.38 and 2.0.0-alpha.1 through 2.0.0-RC.2 allows remote attackers to hijack accounts via AICC requests. The anonymous main/lp/aicc_hacp.php endpoint passes the aicc_sid or session_id request value to PHP's session_id() before global bootstrap, binding subsequent activity to an attacker-known identifier. Exploitation requires a victim to use the fixed session and authenticate; the attacker can then reuse the known identifier to act as that victim, including an administrator.

CVSS severity8.8
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session fixation in Chamilo LMS before 1.11.38 and 2.0.0-alpha.1 through 2.0.0-RC.2 allows remote attackers to hijack accounts via AICC requests. The anonymous main/lp/aicc_hacp.php endpoint passes the aicc_sid or session_id request value to PHP's session_id() before global bootstrap, binding subsequent activity to an attacker-known identifier. Exploitation requires a victim to use the fixed session and authenticate; the attacker can then reuse the known identifier to act as that victim, including an administrator.

The record

CVE
CVE-2026-31940
Published
Apr 10, 2026
Updated
Apr 10, 2026
Vendor
Chamilo
Product
Chamilo LMS
Classifications
CWE-384, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 10, 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
  2. Affected versionversion=>= 2.0.0-alpha.1, < 2.0.0-RC.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Chamilo · Chamilo LMSversion=< 1.11.38; version=>= 2.0.0-alpha.1, < 2.0.0-RC.3

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-384Session Fixation
T1550.004Use Alternate Authentication Material: Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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