Vulnerability · Published Jul 15, 2026 · Assigned by GitHub_M

CVE-2026-566799Router: Mass assignment in PATCH /api/settings allows authenticated authorization downgrade

High 8.7

In plain English

A high-severity security flaw in 9router from decolua. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.7High

Exploit odds (30 days)0.4%top 65.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

9Router is an AI router & token saver. Prior to 0.5.4, the PATCH /api/settings endpoint writes the entire request body to persistent settings without a field whitelist, allowing an authenticated user to set security-critical fields such as requireLogin and disable authentication for the whole application, exposing protected routes such as /api/keys and /api/providers to unauthenticated access. This issue is reported as fixed in version 0.5.4.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	9router	0.5.4	GHSA-vmjq-hvgq-2wv4

Affected products (as reported)

Vendor	Product	Versions
decolua	9router	< 0.5.4

Weakness: CWE-915 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

References

https://github.com/decolua/9router/security/advisories/GHSA-vmjq-hvgq-2wv4 x_refsource_CONFIRM