Vulnerability · Published Jun 12, 2026 · Assigned by GitHub_M
CVE-2026-47138Parse Server: Pre-authentication denial of service via client version header regex backtracking
High 8.7
In plain English
A high-severity regular-expression denial of service in parse-server from parse-community. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.77 and 9.9.1-alpha.1, an unauthenticated attacker who knows a publicly-known Parse Application ID can submit a single HTTP request whose client SDK version field contains adversarial input that triggers polynomial backtracking in a request-header parser. The parsing runs before session authentication and before rate limiting on every /parse/* request, so the request consumes seconds to minutes of synchronous CPU on a Node.js worker before any access control evaluates it. A small number of concurrent requests can saturate a worker; a single large request via the body-field variant can pin a worker for minutes. Production deployments running the default configuration are affected. This issue has been patched in versions 8.6.77 and 9.9.1-alpha.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | parse-server | 9.9.1-alpha.1 | GHSA-38m6-82c8-4xfm |
| npm | parse-server | 8.6.77 | GHSA-38m6-82c8-4xfm |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| parse-community | parse-server | < 8.6.77>= 9.0.0, < 9.9.1-alpha.1 |
Weakness: CWE-1333 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
References
- https://github.com/parse-community/parse-server/security/advisories/GHSA-38m6-82c8-4xfm x_refsource_CONFIRM
- https://github.com/parse-community/parse-server/pull/10463 x_refsource_MISC
- https://github.com/parse-community/parse-server/pull/10464 x_refsource_MISC