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 CephX authentication protocol encrypts tickets with AES-128-CBC in an unauthenticated mode that uses a hard-coded initialization vector and no message authentication, allowing an attacker to forge credentials and gain cluster-wide access. Because the ciphertext is malleable and the monitor will encrypt attacker-chosen entity names, an attacker holding one low-privilege key and able to observe CephX traffic can use the monitor as an encryption oracle and splice ciphertext blocks into valid tickets for privileged entities such as Manager, MDS, and OSD. The same lack of authentication also lets an attacker with CephX permissions escalate privileges by flipping a single bit in a service ticket to set its allow_all field to true. This issue is fixed in versions 20.2.4 and 19.2.6.
History

Fri, 28 Aug 2026 05:45:00 +0000

Type Values Removed Values Added
First Time appeared Ceph
Ceph ceph
Vendors & Products Ceph
Ceph ceph

Thu, 27 Aug 2026 18:00:00 +0000

Type Values Removed Values Added
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 CephX authentication protocol encrypts tickets with AES-128-CBC in an unauthenticated mode that uses a hard-coded initialization vector and no message authentication, allowing an attacker to forge credentials and gain cluster-wide access. Because the ciphertext is malleable and the monitor will encrypt attacker-chosen entity names, an attacker holding one low-privilege key and able to observe CephX traffic can use the monitor as an encryption oracle and splice ciphertext blocks into valid tickets for privileged entities such as Manager, MDS, and OSD. The same lack of authentication also lets an attacker with CephX permissions escalate privileges by flipping a single bit in a service ticket to set its allow_all field to true. This issue is fixed in versions 20.2.4 and 19.2.6.
Title Ceph: AES-CBC misuse in CephX and RADOSGW enables authentication bypass and credential forgery
Weaknesses CWE-327
References
Metrics cvssV3_1

{'score': 8.9, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-27T20:34:41.822Z

Reserved: 2025-03-17T12:41:42.566Z

Link: CVE-2025-30156

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-28T00:16:45.557

Modified: 2026-08-28T00:16:45.557

Link: CVE-2025-30156

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-28T05:30:18Z