Privilege escalation via unsigned SigV4 headers
Published Aug 27, 2026 · Updated Aug 27, 2026
Improper signature verification in Ceph RGW 19.x before 19.2.6 and 20.x before 20.2.4 allows attackers with a presigned PUT URL to alter objects. The SigV4 handler validates only names in X-Amz-SignedHeaders and honors additional unsigned x-amz-* headers instead of rejecting the request. Possession of a presigned PUT URL is required; exploitation can read objects accessible to the signer and modify the target object's data or ACL, without interrupting service.
Summary
What happened
Improper signature verification in Ceph RGW 19.x before 19.2.6 and 20.x before 20.2.4 allows attackers with a presigned PUT URL to alter objects. The SigV4 handler validates only names in X-Amz-SignedHeaders and honors additional unsigned x-amz-* headers instead of rejecting the request. Possession of a presigned PUT URL is required; exploitation can read objects accessible to the signer and modify the target object's data or ACL, without interrupting service.
The record
- CVE
- CVE-2026-54330
- Published
- Aug 27, 2026
- Updated
- Aug 27, 2026
- Vendor
- Ceph
- Product
- Ceph
- Classifications
- CWE-347, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 27, 2026CVE publishedPublication date reported by the CVE source.
- Aug 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 19.0.0, < 19.2.6
- Affected versionversion=>= 20.0.0, < 20.2.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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