Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-43930

Severity CVSS v4.0:
LOW
Type:
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Publication date:
12/05/2026
Last modified:
13/05/2026

Description

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 8.6.76 and 9.9.0-alpha.2, a race condition in the MFA SMS one-time password (OTP) login path allows two concurrent /login requests carrying the same OTP to both succeed and both receive valid session tokens, breaking the single-use property of the OTP. The vulnerability requires the attacker to already possess the victim's password and intercept the active SMS OTP (e.g. via SIM swap, network mirror, or phishing relay) and to race the legitimate login request, so the practical attack surface is narrow. This vulnerability is fixed in 8.6.76 and 9.9.0-alpha.2.

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 2.10 LOW
Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): High
Attack Requirements (AT): None
Privileges Required (PR): High
User Interaction (UI): None
Confidentiality (VC): None
Integrity (VI): Low
Availability (VA): None
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None

Base Score 4.0
2.10
Severity 4.0
LOW

References to Advisories, Solutions, and Tools