CVE-2026-54330 Ceph RGW SigV4 handler accepts unsigned x-amz-* headers on presigned requests, allowing privilege escalation
Attackers can escalate privileges by adding unsigned headers to presigned URLs in Ceph RGW, bypassing intended access controls.
- 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-2026-54330?
CVE-2026-54330 is a high-severity authentication bypass vulnerability in ceph, published on 27 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Ceph is an open-source distributed storage platform providing object, block, and file storage. In versions prior to 20.2.4 and 19.2.6, the Ceph Object Gateway (RGW) SigV4 handler does not reject requests that carry x-amz-* headers absent from the signed header set, allowing anyone holding a presigned URL to attach arbitrary unsigned x-amz-* headers that RGW will honor. AWS S3 requires every x-amz-* header on a SigV4 request to be signed and rejects requests bearing additional unsigned headers, but RGW validates only the headers listed in X-Amz-SignedHeaders and ignores any extra ones, so they take effect without being covered by the signature. By adding such headers to a presigned PUT URL, an attacker can grant themselves more capabilities than the URL's signer intended and escalate their privileges. This issue is fixed in versions 20.2.4 and 19.2.6.
Weakness: CWE-347
Which versions are affected by CVE-2026-54330?
1 open source package ship an affected version, including ceph.
| Package | Affected | Fixed in |
|---|---|---|
ceph Bitnami | From 19.0.0 | 19.2.6, 20.2.4 |
How do I fix CVE-2026-54330?
Upgrade ceph to a fixed version for your release line: 19.2.6 or 20.2.4.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-54330 being exploited?
There is no known exploitation of CVE-2026-54330 in the wild and no public exploit code.
Sources
Also known as AZL-98340, BIT-ceph-2026-54330, DEBIAN-CVE-2026-54330, ECHO-ba60-36e6-9bcf, GHSA-rmjq-ffrm-j6vj, MINI-f5cf-gmhp-52ch and 3 more.