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

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.

Source published

12 May 2026 13:34:50 UTC

Source modified

13 May 2026 14:27:47 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 2.1 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