CVE-2026-33710 chamilo CVE debrief

Who should care

Defenders responsible for Chamilo LMS deployments should assess exposure and prioritize upgrading to fixed versions. This includes operators, platform administrators, vulnerability management teams, and security teams who need to verify affected scope, severity, and vendor guidance. They should review compensating controls for exposed systems while remediation is scheduled and verified, and track exceptions, retest remediated assets, and close the item .

Why it matters

CVE-2026-33710 is a vulnerability in Chamilo LMS that allows an attacker to brute-force REST API keys. Defenders should prioritize verifying exposure and upgrading to fixed versions.

• An attacker could potentially gain unauthorized access to the LMS
• Defenders need to verify exposure and upgrade to fixed versions
• The vulnerability requires verification of affected versions and remediation priority

Technical summary

The REST API key generation formula in Chamilo LMS is predictable, allowing an attacker to brute-force API keys if they know a username and approximate key creation time. The formula uses md5(time() + (user_id * 5) - rand(10000, 10000)), but the rand(10000, 10000) call always returns exactly 10000, making the formula effectively md5(timestamp + user_id*5 - 10000). This vulnerability can be mitigated by upgrading to versions 1.11.38 or 2.0.0-RC.3 or later. Defenders should prioritize verifying exposure and upgrading to fixed versions.

Defensive priority

Defenders should prioritize verifying exposure and upgrading to fixed versions.

Recommended defensive actions

• Verify exposure by checking if the LMS is using a vulnerable version
• Upgrade to version 1.11.38 or 2.0.0-RC.3 or later
• Monitor for suspicious API activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is caused by the predictable nature of the REST API key generation formula, which uses md5(time() + (user_id * 5) - rand(10000, 10000)). The rand(10000, 10000) call always returns exactly 10000, making the formula effectively md5(timestamp + user_id*5 - 10000).

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.