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SeaweedFS: Unauthenticated filer IAM gRPC service grants S3 administrative control

Critical severity GitHub Reviewed Published Jul 8, 2026 in seaweedfs/seaweedfs • Updated Sep 2, 2026

Package

gomod github.com/seaweedfs/seaweedfs (Go)

Affected versions

< 0.0.0-20260512171108-5e8f99f40a8a

Patched versions

0.0.0-20260512171108-5e8f99f40a8a

Description

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.

Affected component

  • weed/server/filer_server_handlers_iam_grpc.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.filer_signing.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.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

References

@chrislusf chrislusf published to seaweedfs/seaweedfs Jul 8, 2026
Published by the National Vulnerability Database Aug 11, 2026
Published to the GitHub Advisory Database Sep 2, 2026
Reviewed Sep 2, 2026
Last updated Sep 2, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(34th percentile)

Weaknesses

Missing Authentication for Critical Function

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. Learn more on MITRE.

CVE ID

CVE-2026-72920

GHSA ID

GHSA-2v6v-25fm-p4fg

Source code

Credits

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