CVE-2026-53636 Open edX LTI OAuth Replay Attack
Attackers can replay captured LTI launch requests indefinitely due to missing nonce and timestamp validation in the Open edX LMS platform.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-53636?
CVE-2026-53636 is a medium-severity vulnerability in openedx-platform, published on 2 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-294
Which versions are affected by CVE-2026-53636?
How do I fix CVE-2026-53636?
No fix has been published for CVE-2026-53636 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-53636 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53636 exists.
Sources
Also known as GHSA-6gm5-c49g-p3h9.