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TI-2026-28807 Aliases CVE-2026-39944

Ceph: CephX AES Authentication error

Priority MEDIUM 40CWE-327Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 2 fixed, 5 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-327.

Summary

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 RADOS Gateway (RGW) protects STS session tokens with an AES-128-CBC handler that provides no message authentication, allowing an attacker who holds any valid STS token to tamper with it undetected and escalate to full RGW administrative access. Because the ciphertext is unauthenticated, the attacker can perform a CBC bit-flip on the acct_type, perm_type, and is_admin fields of their own token, and a forged is_admin value triggers a global administrative override that bypasses all capability checks. The attack is reachable remotely over the RGW S3 endpoint and is a self-contained modification of a token the attacker already possesses, requiring no encryption oracle and no network observation. It requires only a single valid STS token, which need not carry any elevated privileges, with STS enabled. This issue is fixed in versions 20.2.4 and 19.2.6.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00285 21st percentileScored 2026-11-07
Fix Partial ceph (ceph): 19.2.6, 20.2.4Red Hat: 2 advisoriesRed Hat: 2 fixed, 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
cephceph19.0.0 to before 19.2.6; 20.0.0 to before 20.2.419.2.6, 20.2.4Patch availableCNA
  • ceph Vendorceph Affected 19.0.0 to before 19.2.6; 20.0.0 to before 20.2.4 Fixed in 19.2.6, 20.2.4 Patch available CNA

Remediation

  • Fix · CNA ceph (ceph) Fixed in 19.2.6, 20.2.4

Red Hat 2 advisories

  • RHSA-2026:79243 Released 2026-10-08 · Red Hat rating Important
    Red Hat Ceph Storage
    • Red Hat Ceph Storage 8.1 registry.redhat.io/rhceph/grafana-rhel9, registry.redhat.io/rhceph/rhceph-8-rhel9
  • RHSA-2026:79101 Released 2026-10-08 · Red Hat rating Important
    Red Hat Ceph Storage 8.1 security and bug fix updates
    • Red Hat Ceph Storage 8.1 Tools ceph-2:19.2.1-423.el9cp, ceph-base-2:19.2.1-423.el9cp, ceph-common-2:19.2.1-423.el9cp +25

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Ceph Storage 4AffectedNo fix yet: Fix deferred
Red Hat Ceph Storage 5AffectedNo fix yet: Fix deferred
Red Hat Ceph Storage 6AffectedNo fix yet: Fix deferred
Red Hat Ceph Storage 7AffectedNo fix yet: Fix deferred
Red Hat Ceph Storage 9AffectedNo fix yet: Fix deferred
Red Hat Ceph Storage 8.1Fixed RHSA-2026:79243
Red Hat Ceph Storage 8.1 ToolsFixed RHSA-2026:79101
Not affected: 1 product
  • Red Hat Ceph Storage 8.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-39944
  2. 2026-10-09 Fix available: RHSA-2026:79101 · Red Hat
  3. 2026-10-09 Fix available: RHSA-2026:79243 · Red Hat
  4. 2026-10-09 Fix available: Red Hat Ceph Storage 8.1, Red Hat Ceph Storage 8.1 Tools · Red Hat

References

Other 3

  • TI-2024-32613 Ceph is vulnerable to authentication bypass through RadosGW CVSS 3.1HIGH 8.1
  • TI-2024-32120 RGW DoS attack with empty HTTP header in S3 object copy CVSS 3.1HIGH 7.5
  • TI-2026-36920 Improper authorization in ceph CVSS 3.1CRITICAL 9.1
  • TI-2020-01660 Hard-coded credentials in ceph-ansible CVSS 3.1HIGH 8.8
  • TI-2018-07675 Improper authorization in Red Hat ceph CVSS 3.0HIGH 8.1
  • TI-2019-07542 Improper handling of exceptional conditions in ceph CVSS 3.1HIGH 7.5
See all 17 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences