Parse Server: Race condition in transactional batch requests
Summary
Parse Server 5.4.0 before 8.6.96 and 9.0.0 before 9.10.2-alpha.5 share transactional batch state across concurrent requests. Any client that sends a transactional batch request can interfere with other clients' database writes. On PostgreSQL or MongoDB replica sets and sharded clusters, acknowledged writes of other clients can be rolled back if the batch fails, and PostgreSQL transactions can stay open indefinitely, causing later writes to fail. No privileges or user interaction are required, so the risk is highest for internet-facing Parse APIs.
Affected
- parse-server 5.4.0 to before 8.6.96
- parse-server 9.0.0 to before 9.10.2-alpha.5
Fixed in
- 8.x line: 8.6.96
- 9.x line: 9.10.2-alpha.5 (stable 9.10.2 includes the same fix)
Workaround
- Set the Parse Server option masterKey to a string instead of a function.
- Do not register Cloud Code validators with rateLimit, and do not set Parse.Server after the server has started.
Exploitation
- Unknown. No known exploitation found; not verified against the CISA KEV catalogue.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact partial.
Our recommendation
- Inventory all Parse Server instances and their versions, including transitive npm dependencies.
- Upgrade to 8.6.96 or later on the 8.x line, or 9.10.2 or later on the 9.x line.
- Until patched, apply the workaround and check whether your application sends transactional batch requests.
- Restrict which clients can reach the Parse API.
- Check PostgreSQL for long-running open transactions and review failed batch writes.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-jhh9-hrgh-c9gv github.com
- VulnCheck advisory www.vulncheck.com
- Fix for Parse Server 8 (pull request 10716) github.com
- Fix for Parse Server 9 (pull request 10713) github.com
- Parse Server release 9.10.2-alpha.5 github.com
- Parse Server release 9.10.2 github.com
- OSV entry BIT-parse-2026-109954 osv.dev
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 13:51.
Original description (NVD)
Parse Server 5.4.0 before 8.6.96 and 9.0.0 before 9.10.2-alpha.5 shares transactional batch state across concurrent requests, letting any client's transactional batch request interfere with other clients' database writes. On PostgreSQL or MongoDB replica sets and sharded clusters, other clients' acknowledged writes are rolled back if the batch fails, and PostgreSQL transactions can remain open indefinitely, causing subsequent writes to fail.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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