What is CVE-2026-43930?

CVE-2026-43930 is a medium-severity vulnerability in Parse-Community Parse-Server, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 5.9/10. Published 2026-05-12.

How severe is CVE-2026-43930?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Parse-Community Parse-Server

CVE-2026-43930

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.

Vulnerability class: Race Condition

Published 2026-05-12 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.003 (20.2th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 20.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Parse-Community Parse-Server — versions >= 9.0.0, < 9.9.0-alpha.2, < 8.6.76
Parseplatform Parse-Server — versions 9.9.0

Weakness classification (CWE)

CWE-362 — Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition)

References

github.com/parse-community/parse-server/security/advisories/GHSA-jpq4-7fmq-q5fj (Mitigation, Vendor Advisory)
github.com/parse-community/parse-server/pull/10448 (Patch, Issue Tracking)
github.com/parse-community/parse-server/pull/10449 (Patch, Issue Tracking)

Frequently asked questions

What is CVE-2026-43930?: CVE-2026-43930 is a medium-severity vulnerability in Parse-Community Parse-Server, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 5.9/10. Published 2026-05-12.
How severe is CVE-2026-43930?: Medium severity. CVSS v3 base score is 5.9 out of 10.