CVE-2026-72920: SeaweedFS: Unauthenticated filer IAM gRPC service grants S3 administrative control
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 allowedcommonNames ACL applies to the port rather than to individual RPCs, so any cluster mesh certificate could reach these administrative calls.
Affected component - weed/server/filerserverhandlersiamgrpc.go - weed/command/filer.go
Patches Fixed in 4.24. Every IAM RPC now requires a Bearer token signed with the filer admin signing key (jwt.filersigning.key), and the service refuses to register when no signing key is configured — removing the unauthenticated default entirely.
Workarounds Restrict the filer gRPC port to trusted hosts. Configure jwt.filersigning.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)
Other sources
SeaweedFS is a distributed storage system. Prior to 4.24, the filer registers the SeaweedIdentityAccessManagement gRPC service without mandatory authentication when jwt.filersigning.key is unset, allowing any client that can reach the filer gRPC port to invoke CreateUser, CreateAccessKey, PutPolicy, and related IAM RPCs to mint credentials and gain S3 administrative control. This issue is fixed in versions 4.24.
— NVD
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
go/github.com/seaweedfs/seaweedfsto a version that resolves this vulnerability.Fixed in 0.0.0-20260512171108-5e8f99f40a8a - Upgrade
Upgrade
seaweedfs/seaweedfsto a version that resolves this vulnerability.Fixed in 4.24 - Configuration
Set `jwt.filer_signing.key` in `security.toml` as part of the JWT signing key configuration for the filer.
SeaweedFS filer (security.toml) jwt.filer_signing.key = (configure with a signing key) - Compensating control
Restrict the filer gRPC port to trusted hosts (listener-level access control), since reachability to the filer gRPC port allows IAM RPCs.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-72920?
The severity of CVE-2026-72920 is rated as critical with a score of 9.8.
What does CVE-2026-72920 affect?
CVE-2026-72920 affects the SeaweedFS distributed storage system, specifically its unauthenticated gRPC service.
How do I fix CVE-2026-72920?
To fix CVE-2026-72920, set the jwt.filer_signing.key to enforce authentication on the SeaweedIdentityAccessManagement gRPC service.
What are the risks of CVE-2026-72920?
CVE-2026-72920 allows unauthenticated clients to gain administrative control over S3 operations, posing significant security risks.
When was CVE-2026-72920 published?
CVE-2026-72920 was published on August 11, 2026.