Authentication bypass via unchecked OAuth nonce replay
Published Sep 2, 2026 · Updated Sep 2, 2026
Authentication bypass in Open edX Platform before commit 3a5ac85 allows attackers to assume an LTI user's identity via a captured launch request. The LTI Provider's validate_timestamp_and_nonce function returns true without checking timestamp freshness or recording and rejecting reused OAuth nonces. Exploitation requires capturing a valid signed LTI launch and a victim's interaction; replay grants the victim's course access and permitted actions.
Summary
What happened
Authentication bypass in Open edX Platform before commit 3a5ac85 allows attackers to assume an LTI user's identity via a captured launch request. The LTI Provider's validate_timestamp_and_nonce function returns true without checking timestamp freshness or recording and rejecting reused OAuth nonces. Exploitation requires capturing a valid signed LTI launch and a victim's interaction; replay grants the victim's course access and permitted actions.
The record
- CVE
- CVE-2026-53636
- Published
- Sep 2, 2026
- Updated
- Sep 2, 2026
- Vendor
- Open edX
- Product
- Open edX Platform
- Classifications
- CWE-294, T1550
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 2, 2026CVE publishedPublication date reported by the CVE source.
- Sep 2, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 3a5ac856c79557c5c74d8b3e6578f289d7cceecd
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Open edX LTI OAuth replay proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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