What is GHSA-56wq-x3wv-3ff4?

GHSA-56wq-x3wv-3ff4 is a security advisory published by GitHub Security Advisories with High severity. SeaweedFS: Path traversal in the S3 gateway X-Amz-Copy-Source header allows cross-bucket object read

Which CVE IDs does GHSA-56wq-x3wv-3ff4 cover?

GHSA-56wq-x3wv-3ff4 covers the following CVE IDs: CVE-2026-55874. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of GHSA-56wq-x3wv-3ff4?

GHSA-56wq-x3wv-3ff4 has a CVSS v3 base score of 7.7, published by GitHub Security Advisories.

Which products are affected by GHSA-56wq-x3wv-3ff4?

GHSA-56wq-x3wv-3ff4 affects 1 product, including: go/github.com/seaweedfs/seaweedfs:\u003c 0.0.0-20260612000715-b44cf51fe931.

GHSA-56wq-x3wv-3ff4HighCVSS 7.7

SeaweedFS: Path traversal in the S3 gateway X-Amz-Copy-Source header allows cross-bucket object read

Vendor

GitHub Security Advisories

Published

August 28, 2026

Last Modified

August 28, 2026

🔗 CVE IDs covered (1)

CVE-2026-55874 →

📋 Description

Summary

The SeaweedFS S3 API gateway did not reject .. path segments in the X-Amz-Copy-Source header used by CopyObject and UploadPartCopy. The request URL path was hardened against traversal in 4.30 (CVE-2026-54917), but the copy-source header was only checked for emptiness, so a .. segment in the copy source survived into the server-side filer path and resolved into a different bucket.

Impact

A confused-deputy authorization bypass that breaks bucket isolation. IAM evaluates the caller's policy against the bucket named in the request URL (the destination the caller owns), while the copy reads its source from the traversed target bucket. An identity scoped to a single bucket (Read + Write on one bucket it controls) can therefore read any object in any bucket on the instance and land the result in its own bucket.

For example, a caller authorized only for bucket-a issues a CopyObject into bucket-a with copy source bucket-a/../<victim-bucket>/<key>; the gateway reads <victim-bucket>/<key> and writes it to the attacker-controlled destination, from which the caller reads it normally. UploadPartCopy (CopyObjectPartHandler) is affected by the same vector.

Affected versions

All releases prior to 4.34. The 4.30 fix for CVE-2026-54917 hardened the request URL path but not the X-Amz-Copy-Source header.

Patched version

4.34 and later.

Remediation

Upgrade to 4.34 or later. The fix validates the copy-source bucket and object key with the same IsValidBucketName / IsValidObjectKey guards already applied to the request URL, rejecting traversal segments before the handler runs, and applies the same check to UploadPartCopy.

Workaround

No configuration workaround. For deployments that cannot upgrade immediately, front the gateway with a reverse proxy that rejects requests whose X-Amz-Copy-Source header contains .., %2e%2e, or backslash sequences.

References

Fix: https://github.com/seaweedfs/seaweedfs/pull/9929 (commit b44cf51fe931bd75aa4d37ae766bea90d7f85ccd)