CVE-2026-53636

Open edX LTI OAuth Replay Attack

MEDIUM
4.7
CVSS Score
Published: September 2, 2026 at 04:54 PM UTC
Updated: September 9, 2026 at 09:17 PM UTC
1 product affected across 1 vendorOpenedx

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Severity
MEDIUM4.7
Exploit prediction
EPSS 0.3%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3a5ac856c79557c5c74d8b3e6578f289d7cceecd

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.7MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-294

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