What is the CVSS score of EUVD-2026-21522?

EUVD-2026-21522 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%.

Which versions of PHP are affected by EUVD-2026-21522?

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.

How to fix or mitigate EUVD-2026-21522?

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.

PHP EUVD-2026-21522

| CVE-2026-31940 HIGH

Session Fixation (CWE-384)

2026-04-10 GitHub_M

PHP Information Disclosure Session Fixation

7.5

CVSS 3.1 · GitHub Advisory

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

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Re-analysis Queued

Apr 17, 2026 - 21:37 vuln.today

cvss_changed

Analysis Updated

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

executive_summary

Re-analysis Queued

Apr 16, 2026 - 05:29 backfill_euvd_patch

patch_released

Patch available

Apr 16, 2026 - 05:29 EUVD

2.0.0-RC.3,1.11.38

EUVD ID Assigned

Apr 10, 2026 - 18:00 euvd

EUVD-2026-21522

Analysis Generated

Apr 10, 2026 - 18:00 vuln.today

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.

AnalysisAI

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.

Technical ContextAI

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).

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.