Summary
SeaweedFS: Unauthenticated filer IAM gRPC service grants S3 administrative control
Affected component
weed/server/filer_server_handlers_iam_grpc.goweed/command/filer.go
Workarounds
Restrict the filer gRPC port to trusted hosts. Configure jwt.filer_signing.key in security.toml and upgrade to 4.24; operators that use the IAM RPCs must attach an admin-signed Bearer token on each call.
References
- Fixed by seaweedfs/seaweedfs#9442 (follow-ups: #9498, #9508, #9514, #9536)
- Reported by Kadir Arslan (https://github.com/KadirArslan)
Impact
The filer registered the IAM gRPC service (SeaweedIdentityAccessManagement) with no authentication. Any client able to reach the filer gRPC port could invoke IAM RPCs, CreateUser, CreateAccessKey, PutUserPolicy, and related calls, to mint credentials and grant itself S3 administrative privileges. This fully compromises the confidentiality, integrity, and availability of stored objects.
No credentials are required, and enabling the documented JWT signing keys does not close it: the IAM gRPC service was not gated by that mechanism. Even under mTLS, the listener-level allowed_commonNames ACL applies to the port rather than to individual RPCs, so any cluster mesh certificate could reach these administrative calls.
A critical operation is accessible without requiring any authentication. Typical impact: any user can invoke the privileged function.
CVE-2026-72920 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.0.0-20260512171108-5e8f99f40a8a); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed in 4.24. Every IAM RPC now requires a Bearer token signed with the filer admin signing key (jwt.filer_signing.key), and the service refuses to register when no signing key is configured, removing the unauthenticated default entirely.
Frequently Asked Questions
- What is CVE-2026-72920? CVE-2026-72920 is a critical-severity missing authentication for critical function vulnerability in github.com/seaweedfs/seaweedfs (go), affecting versions < 0.0.0-20260512171108-5e8f99f40a8a. It is fixed in 0.0.0-20260512171108-5e8f99f40a8a. A critical operation is accessible without requiring any authentication.
- How severe is CVE-2026-72920? CVE-2026-72920 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/seaweedfs/seaweedfs are affected by CVE-2026-72920? github.com/seaweedfs/seaweedfs (go) versions < 0.0.0-20260512171108-5e8f99f40a8a is affected.
- Is there a fix for CVE-2026-72920? Yes. CVE-2026-72920 is fixed in 0.0.0-20260512171108-5e8f99f40a8a. Upgrade to this version or later.
- Is CVE-2026-72920 exploitable, and should I be worried? Whether CVE-2026-72920 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-72920 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-72920? Upgrade
github.com/seaweedfs/seaweedfsto 0.0.0-20260512171108-5e8f99f40a8a or later.