What’s Vulnerable › Vulnerabilities

CVE-2026-43930: Parse Server: MFA SMS one-time password accepted twice under concurrent login

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-12 · updated 2026-10-26
• Weakness: CWE-362

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.

Affected products

• parse-community parse-server: before 8.6.76; from 9.0.0 before 9.9.0; 9.9.0-alpha1 — fixed in 8.6.76, 9.9.0

How to fix

Upgrade to a fixed version: parse-community parse-server 8.6.76, 9.9.0. Check the vendor advisory for mitigations.

References

• https://github.com/parse-community/parse-server/pull/10448
• https://github.com/parse-community/parse-server/pull/10449
• https://github.com/parse-community/parse-server/security/advisories/GHSA-jpq4-7fmq-q5fj

Get alerted when CVE-2026-43930 or the next vulnerability affects your stack