CVE-2026-77298 SeaweedFS S3 OIDC Bearer authentication bypasses IAM role trust policy
SeaweedFS S3 API allows federated users to bypass IAM trust policies and assume unauthorized roles, gaining read, write, and delete access to stored objects.
- 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-2026-77298?
CVE-2026-77298 is a high-severity authentication bypass 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 4.39 and earlier, the S3 API accepts an external OIDC JWT sent directly in the Authorization header and maps it to an IAM role without enforcing that role's trust policy, so a federated user can assume a role they are not permitted to hold. The standard STS AssumeRoleWithWebIdentity path rejects such a token when the role's trust policy does not trust the token's federated provider, but the direct S3 bearer path validates only the token itself and then authenticates as the mapped role and evaluates that role's attached S3 permissions. As a result, a valid OIDC user whose token would be denied the role through STS can obtain the role's S3 access, including object read, write, and delete, by presenting the raw OIDC JWT directly to the S3 API. This issue is fixed in version 4.40
Weakness: CWE-863
Which versions are affected by CVE-2026-77298?
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-2026-77298?
Upgrade seaweedfs to 4.40.0 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-77298 being exploited?
There is no known exploitation of CVE-2026-77298 in the wild and no public exploit code.
Sources
Also known as BIT-seaweedfs-2026-77298, GHSA-757h-cm9x-wprg, MINI-jwm5-65w2-v6vh.