What is the CVSS score of CVE-2026-31940?

CVE-2026-31940 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-31940?

Within 24 hours: Identify all Chamilo LMS instances in production and document current versions. Within 7 days: Upgrade Chamilo to version 1.11.38 or later (for 1.x branch) or 2.0.0-RC.3 or later (for 2.0 branch); test in staging environment first. Within 30 days: Verify all instances have been patched, conduct session audit to identify any unauthorized access, and review access logs for exploitation attempts targeting main/lp/aicc_hacp.php.

Chamilo Lms CVE-2026-31940

Q: Which versions of Chamilo Lms are affected by CVE-2026-31940?

Chamilo LMS versions before 1.11.38 and 2.0.0-RC.3 contain a session fixation vulnerability that allows unauthenticated attackers to hijack user sessions and gain unauthorized access to student…. A patch is available.

EUVD-2026-21522 HIGH

Session Fixation (CWE-384)

2026-04-10 GitHub_M

PHP Information Disclosure Session Fixation Chamilo Lms Chamilo

7.5

CVSS 3.1 · GitHub Advisory

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Craft malicious URL with session ID parameter
Delivery

Trick user into clicking link
Exploit

Session ID set before bootstrap loads
Execution

Attacker hijacks authenticated session
Impact

Access victim's LMS account and data

Vulnerability Assessment

Weakness	CWE CWE-384 OWASP Top 10:2025 A07:2025 - Authentication Failures ASVS 5.0 V7 - Session Management Session fixation prevention
Exploitation Conditions	Remote unauthenticated attacker crafts a malicious URL with controlled session ID parameters targeting main/lp/aicc_hacp.php in Chamilo LMS versions before 1.11.38 or 2.0.0-RC.3. Victim must click the link. Requires victim to subsequently authenticate for session fixation impact.
Impact	Session fixation in Chamilo LMS affects unauthenticated users via network access but requires user interaction and high attack complexity. CVSS 7.5 reflects high confidentiality/integrity impact. No KEV or EPSS data available; remediation is available in patched versions 1.11.38 and 2.0.0-RC.3. Priority depends on deployment prevalence and patch adoption rates.
Exploit ScenarioDerived	Attacker crafts malicious link with fixed session ID in request parameter to main/lp/aicc_hacp.php. When victim clicks link, their session is set to attacker-controlled ID, enabling account hijacking or unauthorized access to learning records. User interaction required; no public exploit code identified at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 10, 2026

Session fixation in Chamilo LMS versions prior to 1.11.38 and 2.0.0-RC.3 enables unauthenticated remote attackers to hijack user sessions via main/lp/aicc_hacp.php. User-controlled request parameters directly manipulate PHP session IDs before application bootstrap, allowing attackers to force victims into attacker-controlled sessions. Successful exploitation grants high-severity access to confidential data and platform integrity. No public exploit identified at time of analysis.

RemediationAI

Vendor-released patches: upgrade to Chamilo LMS version 1.11.38 (for 1.x branch) or 2.0.0-RC.3 (for 2.x branch). Upstream fixes available via commits ce0192c62e48c9d9474d915c541b3274844afbf9 and e337b7cc74a0276a0b4f91f9282204d20cac1869, which enforce session ID regeneration and input validation. Official security advisory: https://github.com/chamilo/chamilo-lms/security/advisories/GHSA-4gp7-cfjh-77gv. Temporary mitigation: restrict network access to /main/lp/aicc_hacp.php via web application firewall rules or disable AICC HACP functionality if not operationally required. Implement HTTP Strict-Transport-Security and secure session cookie attributes (HttpOnly, Secure, SameSite) to reduce session hijacking surface area.

Affected VersionsENISA

chamilo-lms 2.0.0-alpha.1, < 2.0.0-RC.3

chamilo-lms < 1.11.38

Affected Packages

euvd chamilo_lms fix: 1.11.38

euvd chamilo_lms_2_0_0_alpha_1 fix: 2.0.0-RC.3

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Root cause resides in main/lp/aicc_hacp.php accepting external input for session ID assignment prior to security context initialization. PHP session handling lacks validation of session origin, violating CWE-384 constraints. The vulnerable endpoint processes AICC HACP protocol parameters without sanitization, creating a pre-authentication attack surface exploitable through social engineering (CVSS UI:R).

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 7.5 HIGH

AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Updated

Apr 16, 2026 - 05:58 EUVD-patch-fix

executive summary

Patch available

Apr 16, 2026 - 05:29 EUVD

2.0.0-RC.3,1.11.38

CVE Published

Apr 10, 2026 - 17:35 nvd

HIGH 7.5

DescriptionGitHub Advisory

Chamilo LMS is a learning management system. Prior to 1.11.38 and 2.0.0-RC.3, in main/lp/aicc_hacp.php, user-controlled request parameters are directly used to set the PHP session ID before loading global bootstrap. This leads to session fixation. This vulnerability is fixed in 1.11.38 and 2.0.0-RC.3.

Executive ViewAI

Why It Matters

Chamilo LMS versions before 1.11.38 and 2.0.0-RC.3 contain a session fixation vulnerability that allows unauthenticated attackers to hijack user sessions and gain unauthorized access to student records, course materials, and instructor accounts. Organizations running affected Chamilo instances face immediate risk of data breach and compromise of learning platform integrity without remediation.

Business Impact: High

Compensating Controls

Apply vendor patch. If immediate upgrade is not feasible: restrict network access to Chamilo instances using WAF rules or network ACLs to block unauthenticated requests to main/lp/aicc_hacp.php; invalidate all active sessions and force re-authentication; implement session ID regeneration policies; monitor access logs for suspicious session parameter manipulation.

Threat Intelligence Overview

EPSS Score

0.0%

Top 89% exploitable

Data Quality

5 sources

Confidence: Medium

EUVD

NVD

CVE.org

EPSS

Vulnrichment

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision

Scheduled

Exploitation

None

System Exposure· derived

Open

Automatable

Human Impact

High

Technical Impact

Total

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +38

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.