CVE-2026-33624
Parse Server: MFA recovery code single-use bypass via concurrent requests
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.60 and 9.6.0-alpha.54, an attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds. This issue has been patched in versions 8.6.60 and 9.6.0-alpha.54.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Parse Server: MFA recovery code single-use bypass via concurrent requests
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.60 and 9.6.0-alpha.54, an attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds. This issue has been patched in versions 8.6.60 and 9.6.0-alpha.54.
- Record
CVE-2026-33624- CVSS 4.0
- 2.1 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-367
- Updated
- 2026-11-02
EUVDEUVD-2026-14978
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.60 and 9.6.0-alpha.54, an attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds. This issue has been patched in versions 8.6.60 and 9.6.0-alpha.54.
- Record
EUVD-2026-14978- CVSS 4.0
- 2.1 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-2299-ghjr-6vjp
Parse Server: MFA recovery code single-use bypass via concurrent requests
Impact
An attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds.
Patches
The login handler now uses optimistic locking when updating auth data that contains consumed single-use tokens. If a concurrent request has already modified the recovery array, the update fails and the login is rejected.
Workarounds
There are no known workarounds.
- Record
GHSA-2299-ghjr-6vjp- CVSS 4.0
- 2.1 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-367
- Updated
- 2026-11-02
NVD
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.60 and 9.6.0-alpha.54, an attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds. This issue has been patched in versions 8.6.60 and 9.6.0-alpha.54.
- Record
CVE-2026-33624- CVSS 4.0
- 2.1 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 2.7 Low
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-367
- Updated
- 2026-11-02
OSV
Parse Server: MFA recovery code single-use bypass via concurrent requests
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.60 and 9.6.0-alpha.54, an attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds. This issue has been patched in versions 8.6.60 and 9.6.0-alpha.54.
- Record
CVE-2026-33624- CVSS 4.0
- 2.1 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-367
- Updated
- 2026-11-02
OSVGHSA-2299-ghjr-6vjp
Parse Server: MFA recovery code single-use bypass via concurrent requests
Impact
An attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds.
Patches
The login handler now uses optimistic locking when updating auth data that contains consumed single-use tokens. If a concurrent request has already modified the recovery array, the update fails and the login is rejected.
Workarounds
There are no known workarounds.
- Record
GHSA-2299-ghjr-6vjp- CVSS 4.0
- 2.1 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-367
- Updated
- 2026-11-02
OSVBIT-parse-2026-33624 No score
Parse Server: MFA recovery code single-use bypass via concurrent requests
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.60 and 9.6.0, an attacker who obtains a user's password and a single MFA recovery code can reuse that recovery code an unlimited number of times by sending concurrent login requests. This defeats the single-use design of recovery codes. The attack requires the user's password, a valid recovery code, and the ability to send concurrent requests within milliseconds. This issue has been patched in versions 8.6.60 and 9.6.0
- Record
BIT-parse-2026-33624- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
parse-servernpm |
9.0.0 up to 9.6.0-alpha.54 | 9.6.0-alpha.54 |
parse-servernpm |
before 8.6.60 | 8.6.60 |
parseBitnami |
before 8.6.60, 9.0.0 up to 9.6.0 | 8.6.609.6.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-33624 is a low vulnerability (CVSS 2.1) in Parse-community Parse-server, published March 24, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.18%, the 7th percentile. Fixed in parse-server 9.6.0-alpha.54.
References
github.com/parse-community/parse-server/security/advisories/GHSA-2299-ghjr-6vjp
nvd.nist.gov/vuln/detail/CVE-2026-33624