CVE-2026-55874: SeaweedFS: Path traversal in the S3 gateway X-Amz-Copy-Source header allows cross-bucket object read

Severity: high (CVSS 7.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-08 · updated 2026-07-08
Weakness: CWE-22

Description

SeaweedFS is a distributed storage system. Prior to 4.34, the S3 API gateway does not reject dot-dot path segments in the X-Amz-Copy-Source header used by CopyObject and UploadPartCopy, allowing an authenticated identity scoped to one bucket to read objects from other buckets through server-side copy. This issue is fixed in version 4.34.

Affected products

seaweedfs: before 4.34

References

https://github.com/seaweedfs/seaweedfs/commit/b44cf51fe931bd75aa4d37ae766bea90d7f85ccd
https://github.com/seaweedfs/seaweedfs/pull/9929
https://github.com/seaweedfs/seaweedfs/releases/tag/4.34
https://github.com/seaweedfs/seaweedfs/security/advisories/GHSA-56wq-x3wv-3ff4

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