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.

CVSS Details

CVSS 4.0 Base Score: 2.1 (LOW)
CVSS 4.0 Vector: (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 Base Score: 2.7
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N)

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CVSS Details

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CVE-2026-33624: Time-of-check Time-of-use (TOCTOU) Race Condition

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