RustFS: Reflective CORS with credentials on S3 listener; unauthenticated license metadata endpoint on console
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · Low · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-306.
Summary
RustFS is a distributed object storage system built in Rust. Prior to 1.0.0-beta.2, when RUSTFS_CORS_ALLOWED_ORIGINS is unset, the RustFS S3 listener's ConditionalCorsLayer reflects any request Origin value back as Access-Control-Allow-Origin and also sets Access-Control-Allow-Credentials: true and Access-Control-Allow-Headers: * on responses, including preflight responses and error responses. This creates a permissive cross-domain policy with untrusted origins. A browser visiting an attacker-controlled page can issue credentialed cross-origin requests to a reachable RustFS deployment and read the response when the victim browser has ambient credentials for the RustFS origin, such as saved HTTP Basic Auth credentials, reverse-proxy SSO cookies, or TLS client certificates. This vulnerability is fixed in 1.0.0-beta.2.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA rustfs (rustfs) Fixed in 1.0.0-beta.2
Timeline
- 2026-10-02 Threatist record created from CVE-2026-46685
More rustfs vulnerabilities
- TI-2025-42382 RustFS has a gRPC Hardcoded Token Authentication Bypass CVSS 3.1CRITICAL 9.8
- TI-2026-32895 RustFS: Authentication bypass in /profile/cpu and /profile/memory allows unauthenticated access to profiling handlers CVSS 4.0HIGH 8.8
- TI-2026-32892 RustFS: Hard-coded RSA private key in license verifier permits arbitrary license forgery CVSS 4.0HIGH 8.7
- TI-2025-42176 RustFS Path Traversal Vulnerability CVSS 4.0HIGH 8.8
- TI-2026-36822 RustFS Snowball Auto-Extract: Path Traversal allows cross-bucket object injection CVSS 3.1HIGH 8.6
- TI-2026-32894 RustFS: ImportIam Allows Creation of Backdoor Service Accounts Under Any Parent Including Root CVSS 4.0CRITICAL 9.3
Sources
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