# CVE-2026-53636

## Summary

- **CVE ID:** CVE-2026-53636
- **Severity:** MEDIUM
- **CVSS Score:** 4.7 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N)
- **CWE:** CWE-294
- **Published:** Sep 2, 2026
- **Last Modified:** Sep 2, 2026

## Description

Open edX Platform enables the authoring and delivery of online learning at any scale. Prior to commit 3a5ac85, a security vulnerability has been identified in the Open edX LMS platform's LTI (Learning Tools Interoperability) Provider implementation. The validate_timestamp_and_nonce function in lms/djangoapps/lti_provider/signature_validator.py does not validate OAuth nonces or timestamps, allowing an attacker who captures a valid LTI launch request to replay it an unlimited number of times without detection. This issue has been patched via commit 3a5ac85.

## Affected Products

- openedx — openedx-platform (< 3a5ac856c79557c5c74d8b3e6578f289d7cceecd)

## References

- [CNA](https://github.com/openedx/openedx-platform/security/advisories/GHSA-6gm5-c49g-p3h9)
- [CNA](https://github.com/openedx/openedx-platform/commit/0a92cf25de8844bf840ffd5d18dcfd940031a2ba)
- [CNA](https://github.com/openedx/openedx-platform/commit/3a5ac856c79557c5c74d8b3e6578f289d7cceecd)
- [CNA](https://github.com/openedx/openedx-platform/commit/50af17b05d82a8c7e8e690cc2783a8a0ba330bc3)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.17%
- **EPSS Percentile:** 6.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._