CVE-2026-46685
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedRustFS 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceRustFS S3 listener has a permissive CORS misconfiguration where unset RUSTFS_CORS_ALLOWED_ORIGINS causes the ConditionalCorsLayer to reflect any request Origin header back as Access-Control-Allow-Origin, while simultaneously allowing credentials and all headers. This enables cross-origin attacks where a victim's browser can be tricked into making authenticated requests to RustFS from attacker-controlled pages, exposing sensitive data.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- Authentication
- X
- User interaction
- P
- Scope
- X
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm RustFS S3 listener is deployedIdentify RustFS processes or binaries in your environment running the S3 listener componentAffected if RustFS with S3 listener is actively running
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Check RustFS versionRun `rustfs --version` or inspect the installed RustFS binary/package versionAffected if Version is earlier than 1.0.0-beta.2
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Verify RUSTFS_CORS_ALLOWED_ORIGINS environment variableCheck the environment variables for the RustFS process: `printenv | grep RUSTFS_CORS` or inspect the deployment configurationAffected if RUSTFS_CORS_ALLOWED_ORIGINS is not set or is empty/undefined
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Inspect CORS response headers from S3 listenerSend a request to the RustFS S3 endpoint with an arbitrary Origin header (e.g., `curl -H 'Origin: http://evil.com' -I https://your-rustfs-endpoint`) and inspect the Access-Control-Allow-Origin response headerAffected if The response reflects the arbitrary Origin header exactly (e.g., shows 'http://evil.com') rather than being absent or restricted to a specific allowed list
You are affected if RustFS S3 listener is running with version < 1.0.0-beta.2 and the RUSTFS_CORS_ALLOWED_ORIGINS environment variable is unset or empty, causing the service to reflect arbitrary Origin headers in CORS responses.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedSet the RUSTFS_CORS_ALLOWED_ORIGINS environment variable to explicitly list trusted origin domains, or upgrade to version 1.0.0-beta.2 or later which contains the fix.
1.0.0-beta.2
- Identify the current RustFS version in use by checking the deployed artifact or build configuration
- Stop the RustFS service to prevent exposure during the upgrade
- Upgrade RustFS to version 1.0.0-beta.2 or later, using the project's standard upgrade procedure (e.g., package manager, binary replacement, or container image update)
- After upgrading, verify that the CORS configuration behaves correctly by reviewing the RUSTFS_CORS_ALLOWED_ORIGINS setting - ensure it is explicitly configured with allowed origins rather than left unset
- Restart the RustFS service and confirm it is running the fixed version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-46685 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-46685 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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