8.9

CVE-2025-30156: Ceph: AES-CBC misuse in CephX and RADOSGW enables authentication bypass and credential forgery

Awaiting analysis
AliasesUBUNTU-CVE-2025-30156DEBIAN-CVE-2025-30156
Published 27-08-2026Last modified 01-09-2026

Vulnerability summary

CVE-2025-30156 is a high (CVSS 8.9) vulnerability in ceph. EPSS estimates a 0.09% chance of exploitation in the next 30 days, higher than 0.5% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 8.9, adjacent network); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
8.9/10
010
High · v3.1 (CVE.org)
EPSS score
0.09%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 7
MGASA-2026-0389RHSA-2026:18134RHSA-2026:18587RHSA-2026:27708RHSA-2026:27731RHSA-2026:27735

Timeline

  1. 27-08-2026
    PublishedVulnerability first disclosed.
  2. 01-09-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.09%

Chance of exploitation in the next 30 days

Percentile

1%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.09% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: adjacent network, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ceph1 product
  • ceph< 19.2.6 | ≥ 20.0.0, < 20.2.4
Debian1 product
  • cephAll versions (No fix recorded) | < 20.2.4+ds-1
Ubuntu1 product
  • cephAll versions (No fix recorded)

3 vendors · 3 products

References

7 links