CVE-2026-72920: SeaweedFS: Unauthenticated filer IAM gRPC service grants S3 administrative control

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.8%, percentile 55: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 55% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes github.com/seaweedfs/seaweedfs (Go) < 0.0.0-20260512171108-5e8f99f40a8a, fixed in 0.0.0-20260512171108-5e8f99f40a8a. Check your lockfile, including transitive dependencies.

What it is

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.

From the GitHub advisory

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.

Weakness type: CWE-306.

Product: github.com/seaweedfs/seaweedfs (Go) · Assigned by: GitHub_M · Published: 2026-08-11

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.78% probability of exploitation activity in the next 30 days; percentile 55.

Timeline

• 2026-08-11 — CVE record last updated
• 2026-08-11 — CVE record published by GitHub_M
• 2026-09-02 — GitHub-reviewed advisory GHSA-2v6v-25fm-p4fg published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-2v6v-25fm-p4fg github.com
2. CVE.org record CVE-2026-72920 cve.org
3. NVD entry CVE-2026-72920 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

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