Security-token disclosure via nonconstant UIDL comparison
Published Apr 23, 2021 · Updated Sep 16, 2024
Observable timing discrepancy in affected Vaadin Flow Server releases allows attackers to infer security tokens through UIDL requests. VaadinService.isCsrfTokenValid compares the supplied token with String.equals, so rejection time varies with matching input. Exploitation requires repeated timing measurements and yields blind data submission or access to user-specific WebSocket publications.
Summary
What happened
Observable timing discrepancy in affected Vaadin Flow Server releases allows attackers to infer security tokens through UIDL requests. VaadinService.isCsrfTokenValid compares the supplied token with String.equals, so rejection time varies with matching input. Exploitation requires repeated timing measurements and yields blind data submission or access to user-specific WebSocket publications.
The record
- CVE
- CVE-2021-31404
- Published
- Apr 23, 2021
- Updated
- Sep 16, 2024
- Vendor
- Vaadin
- Product
- Flow Server
- Classifications
- CWE-203, CWE-208
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 23, 2021CVE publishedPublication date reported by the CVE source.
- Sep 16, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.0.0 <* changes=[{"at":"1.1.0","status":"affected"},{"at":"2.0.0","status":"unaffected"},{"at":"2.0.0","status":"affected"},{"at":"3.0.0","status":"affected"},{"at":"5.0.0","status":"unaffected"},{"at":"5.0.0","status":"affected"}]
What conditions does exploitation require?
What is affected?
Published CVSS scores
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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.
Public exploit references
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Technologies
Your stack
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Your stack
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