Cluster-wide credential forgery via unauthenticated AES-CBC
Published Aug 27, 2026 · Updated Aug 27, 2026
Authentication bypass in Ceph before 19.2.6 and 20.0.0 through 20.2.3 allows remote authenticated users to gain cluster-wide access. CephX encrypts tickets with AES-128-CBC using a hard-coded IV and no message authentication, so chosen blocks can be spliced into privileged tickets or bit-flipped to set allow_all. A valid low-privilege CephX key and cluster-network access are required; forged Manager, MDS, or OSD credentials permit data reads, corruption, and administrative control.
Summary
What happened
Authentication bypass in Ceph before 19.2.6 and 20.0.0 through 20.2.3 allows remote authenticated users to gain cluster-wide access. CephX encrypts tickets with AES-128-CBC using a hard-coded IV and no message authentication, so chosen blocks can be spliced into privileged tickets or bit-flipped to set allow_all. A valid low-privilege CephX key and cluster-network access are required; forged Manager, MDS, or OSD credentials permit data reads, corruption, and administrative control.
The record
- CVE
- CVE-2025-30156
- Published
- Aug 27, 2026
- Updated
- Aug 27, 2026
- Vendor
- Ceph
- Product
- Ceph
- Classifications
- CWE-327, T1550
- Attack vector
- adjacent
- 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=< 19.2.6
- 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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