CVE-2026-77611 Missing authorization in seaweedfs
Authenticated users can bypass object-scope restrictions to overwrite unrelated files at the bucket root via PutObjectAcl.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77611?
CVE-2026-77611 is a high-severity missing authorization vulnerability in seaweedfs, published on 26 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
SeaweedFS is a distributed storage system for files and blobs. In versions prior to 4.40, an authenticated S3 principal with permissions scoped to a nested object key can overwrite a different object outside that scope by calling PutObjectAcl on the key it is allowed to access. The handler authorizes the request against the requested nested key but then writes the updated entry back to the bucket root rather than the key's actual parent directory, so an ACL change on allowed/protected.txt is instead applied to protected.txt at the bucket root. Because the update carries the full entry rather than only ACL metadata, an existing target object is overwritten with the content, metadata, owner information, and ACL of the scoped object, bypassing the object-level action scoping configured through the static S3 identity file. This issue is fixed in version 4.40.
Weakness: CWE-863
Which versions are affected by CVE-2026-77611?
1 open source package ship an affected version, including seaweedfs.
| Package | Affected | Fixed in |
|---|---|---|
seaweedfs Bitnami | All versions | 4.40.0 |
How do I fix CVE-2026-77611?
Upgrade seaweedfs to 4.40.0 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-77611 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77611 exists.
Sources
Also known as BIT-seaweedfs-2026-77611, GHSA-9x53-cjpr-m682, MINI-rhv5-hf6x-q63x.