ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 5 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode MDSMap export_targets entries are monitor controlled. check_new_map() uses each entry as a bit number in a fixed stack bitmap, so a rank outside the protocol namespace can make set_bit() write past the end of the array. Reject ranks outside CEPH_MAX_MDS while decoding the map. Do not validate against possible_max_rank here because maps may legitimately reference ranks beyond a temporarily reduced max_mds.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.15.221, 6.1.188, 6.6.157, 6.12.109, 6.18.50, 7.2.4, 7.3
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet |
Not affected: 2 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89653
- 2026-10-03 Alias added: GHSA-q4wh-f6ch-5m9w
- 2026-10-05 EPSS moved to the below the 50th percentile
- 2026-10-18 CISA SSVC decision points changed
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-30 Affected versions changed · Red Hat
References
Other 7
- https://git.kernel.org/stable/c/3740c88ca9cb2210a8dbdd55ea4cec119fbe86fe
- https://git.kernel.org/stable/c/8c823bbab3c24e657469a84db96902ba82d4e8bb
- https://git.kernel.org/stable/c/c4addccd05bacbef2144b4db14853d0308a218ac
- https://git.kernel.org/stable/c/736adee11af36e407ed902264f8b2fb5cf94b62f
- https://git.kernel.org/stable/c/4d298880f82c42383b36946bafde7ccf4d804c9b
- https://git.kernel.org/stable/c/96c3f5fbb0d5386e7111426f047f98cec4586674
- https://git.kernel.org/stable/c/aedc9053d909508a5f56c3f49f885fc030df4730
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Sources
- CVE-2026-89653 · CVE Program
- CVE-2026-89653 · NVD
- FIRST EPSS
- GHSA-q4wh-f6ch-5m9w · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89653 · Red Hat security data · CC BY 4.0
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