CVE-2026-73080: SeaweedFS: Unauthenticated SSRF with response read-back via VolumeServer.FetchAndWriteNeedle

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 0.5%, percentile 44: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 44% of all scored CVEs (low). 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) < 0.0.0-20260512171120-69da20bdaec9, fixed in 0.0.0-20260512171120-69da20bdaec9. Check your lockfile, including transitive dependencies.

What it is

SeaweedFS is a distributed storage system. Prior to 4.24, VolumeServer.FetchAndWriteNeedle in weed/server/volumegrpcremote.go fetches a caller-supplied remote endpoint through weed/remotestorage/s3/s3storageclient.go and writes the response into a needle. The RPC performs no authentication and no target validation, allowing anyone who can reach a volume server's gRPC port to cause requests to arbitrary hosts, including loopback, link-local, RFC 1918, and cloud metadata endpoints such as 169.254.169.254, and read the response. On cloud deployments, this can disclose instance metadata and IAM credentials and reach otherwise unexposed internal services. The volume server gRPC plane is unauthenticated by default, and configuring documented JWT signing keys does not protect this RPC. This issue is fixed in version 4.24.

From the GitHub advisory

Impact VolumeServer.FetchAndWriteNeedle fetches a caller-supplied remote endpoint and writes the response into a needle. Before 4.24 this RPC performed no authentication and no validation of the target, so anyone able to reach a volume server's gRPC port could coerce the server into issuing requests to arbitrary hosts — including loopback, link-local, RFC 1918, and cloud metadata endpoints such as 169.254.169.254 — and read the response back. On cloud deployments this discloses instance metadata and IAM credentials, and can be used to reach otherwise-unexposed internal services (SSRF with response read-back).

The volume server gRPC plane is unauthenticated on a default deployment, so no credentials are required. Configuring the documented JWT signing keys does not close it, because that hardening does not apply to this RPC.

Affected component - weed/server/volumegrpcremote.go (FetchAndWriteNeedle) - weed/remotestorage/s3/s3storageclient.go

Patches Fixed in 4.24. FetchAndWriteNeedle now requires admin authorization and refuses loopback / link-local / RFC 1918 / IMDS destinations through a guarded dialer that resolves the host itself and pins the resolved address for the duration of the request, defeating DNS-rebinding. The Rust volume server carries the equivalent endpoint validation.

Workarounds Restrict volume server gRPC ports to trusted hosts via firewall / network policy, and enable mTLS via security.toml.

Weakness type: CWE-918.

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: changed (can affect other components)

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 partial.
• FIRST EPSS (model of 2026-10-21): 0.53% probability of exploitation activity in the next 30 days; percentile 44.

Timeline

• 2026-08-11 — CVE record published by GitHub_M
• 2026-08-11 — GitHub-reviewed advisory GHSA-87fv-vqqr-m4jr published (critical)
• 2026-08-13 — CVE record last updated

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-87fv-vqqr-m4jr github.com
2. CVE.org record CVE-2026-73080 cve.org
3. NVD entry CVE-2026-73080 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

Critical Go advisories · Today’s Security Digest