CVE-2026-54330
Received Received - Intake

Privilege Escalation in Ceph Object Gateway via Unsigned Headers

Publication date: 2026-08-28

Last updated on: 2026-08-28

Assigner: GitHub, Inc.

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.

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Meta Information

Published
2026-08-28
Last Modified
2026-08-28
Generated
2026-08-28
AI Q&A
2026-08-28
EPSS Evaluated
N/A
NVD
CVE-2026-54330

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
ceph ceph to 19.2.6 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-347 The product does not verify, or incorrectly verifies, the cryptographic signature for data.

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Executive Summary

CVE-2026-54330 is a vulnerability in Ceph's RGW (RADOS Gateway) component affecting SigV4 authentication. It allows attackers with a presigned PUT URL to attach arbitrary unsigned x-amz-* headers, which RGW applies without proper validation. This bypasses signature checks, granting attackers more privileges than intended by the original signer.

Detection Guidance

To detect this vulnerability, check the Ceph version on your system using 'ceph --version'. If it is below 20.2.4 or 19.2.6, the system is vulnerable. Review RGW logs for requests with unsigned x-amz-* headers or missing host headers in SigV4 authentication. Use 'ceph config show' to verify if the rgw_sigv4_insecure option is enabled.

Impact Analysis

An attacker could exploit this to escalate privileges using only a presigned URL, potentially gaining unauthorized access to data or performing actions beyond their intended permissions. This could lead to data breaches, unauthorized modifications, or service disruption in Ceph storage environments.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches, violating confidentiality requirements in GDPR and HIPAA. Organizations using affected Ceph versions may fail compliance audits due to inadequate access controls and improper signature validation.

Mitigation Strategies

Upgrade Ceph to versions 20.2.4 or 19.2.6 or later. For multisite deployments, set 'rgw_sigv4_insecure' to true before upgrading, then set it back to false after all clusters are upgraded. Ensure all x-amz-* headers and host headers are included in the signed header set during SigV4 requests.

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