Linux kernel blk-mq cached requests can stall the Kyber queue
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 4 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
Linux kernel versions from 6.1 are affected in the blk-mq block layer. Cached requests allocated for one operation can be handed out for another, and a passthrough request clears RQF_USE_SCHED, so later read or write requests skip the scheduler's prepare and finish hooks. For the Kyber scheduler, this leaks a domain token and stalls the queue.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: blk-mq: set RQF_USE_SCHED when the operation is known The cached requests are allocated for one operation but can be handed out for another. A passthrough command has RQF_USE_SCHED cleared, so using those flags for a subsequent read/write bio will insert it into the scheduler without ->prepare_request() and frees it without ->finish_request(). For kyber, this leaks the domain token acquired at dispatch and stalls the queue. Don't set RQF_USE_SCHED based on the first operation the batch happened to be allocated for. Instead, set it after the request is claimed by an operation. Introduce a helper function, blk_mq_rq_late_init() for this, and absorb blk_mq_rq_time_init() since the two run together.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Update to Linux kernel 6.18.56, 7.2.10, or 7.3. Red Hat Enterprise Linux 9 and 10 and Red Hat OpenShift Container Platform 4 and 5 are affected, and Red Hat lists no available fix plan for them.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 6.18.56, 7.2.10, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 4 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98820
- 2026-10-18 Alias added: GHSA-95f6-3pp2-9382
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-24 Affected versions changed · Red Hat
- 2026-10-24 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
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Sources
- CVE-2026-98820 · CVE Program
- CVE-2026-98820 · NVD
- FIRST EPSS
- GHSA-95f6-3pp2-9382 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98820 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences