MFA recovery code reuse via concurrent logins
Published Mar 24, 2026 · Updated Mar 24, 2026
Authentication bypass in Parse Server before 8.6.60 and 9.0.0 through 9.6.0-alpha.53 allows remote authenticated users to reuse an MFA recovery code. UsersRouter validates the recovery array, then updates authData by object ID alone, so parallel requests can each remove the same code and create a session. Exploitation requires the user's password, one valid recovery code, MFA enabled, and requests arriving within milliseconds; it yields repeated authenticated sessions.
Summary
What happened
Authentication bypass in Parse Server before 8.6.60 and 9.0.0 through 9.6.0-alpha.53 allows remote authenticated users to reuse an MFA recovery code. UsersRouter validates the recovery array, then updates authData by object ID alone, so parallel requests can each remove the same code and create a session. Exploitation requires the user's password, one valid recovery code, MFA enabled, and requests arriving within milliseconds; it yields repeated authenticated sessions.
The record
- CVE
- CVE-2026-33624
- Published
- Mar 24, 2026
- Updated
- Mar 24, 2026
- Vendor
- Parse Platform
- Product
- Parse Server
- Classifications
- CWE-367, T1078
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 24, 2026CVE publishedPublication date reported by the CVE source.
- Mar 24, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 8.6.60
- Affected versionversion=>= 9.0.0, < 9.6.0-alpha.54
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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