CVE-2026-82535: XSS (CVSS 6.1)

Description

Chamilo LMS before 1.11.42 and 3.0.0 contains a stored cross-site scripting vulnerability that allows unauthenticated attackers to inject malicious script payloads into survey answers by computing deterministic invitation codes and bypassing authorization checks in the survey submission endpoint. Attackers can submit crafted answers containing unescaped HTML rendered in reporting views to execute arbitrary scripts in the browser sessions of teachers or administrators, enabling persistent backdoor account creation by exploiting the victim's authenticated session.

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CVSS v3.1 Score

6.1

MEDIUM

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

EPSS — Exploit Prediction

0.0027

Probability of exploitation

0.19%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/chamilo/chamilo-lms/commit/be45f2f2a29319afbbf9ce27d094698911799d10 https://github.com/chamilo/chamilo-lms/commit/bea9cbcfc6ca58f387c6c25bef2f15dc5df9d147 https://github.com/chamilo/chamilo-lms/commit/c9d2614d798571b94cef1cb61e605a2fc89f0386 https://github.com/chamilo/chamilo-lms/releases/tag/v3.0.0 https://github.com/chamilo/chamilo-lms/security/advisories/GHSA-m3wr-p8wj-jmf6 https://www.vulncheck.com/advisories/chamilo-lms-stored-xss-via-survey-answer-submission-in-reporting-php

Frequently Asked Questions

What is CVE-2026-82535? +

Chamilo LMS before 1.11.42 and 3.0.0 contains a stored cross-site scripting vulnerability that allows unauthenticated attackers to inject malicious script payloads into survey answers by computing deterministic invitation codes and bypassing authorization checks in the survey submission endpoint. Attackers can submit crafted answers containing unescaped HTML rendered in reporting views to execute arbitrary scripts in the browser sessions of teachers or administrators, enabling persistent backdoor account creation by exploiting the victim's authenticated session. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-82535? +

CVE-2026-82535 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0027, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-82535? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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