Out of bounds read in Linux kernel nouveau clock pstate update
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
- Fixed
No CVSS vector from any source. Fix status from CNA.
Summary
The Linux kernel nouveau clock driver (drm/nouveau/clk) mishandles a list cursor in nvkm_clk_ustate_update. When the requested pstate ID is not in the list, or the list is empty, the code dereferences the list head as a pstate, which is an out-of-bounds read. The pstate ID comes from the pstate debugfs file, so a user who can write to that file can trigger the read.
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: drm/nouveau/clk: fix list cursor use after loop in nvkm_clk_ustate_update If list_for_each_entry() exits without hitting a break then "pstate" is not a valid pstate pointer. Introduce a "found" variable instead. The check is reachable from userspace: nvkm_clk_ustate_update() takes the pstate id straight from the 'pstate' debugfs file, so requesting an id that is not in clk->states - or any id at all when the perf tables are broken and the list is empty - makes the pstate->pstate != req test dereference the list head cast to a struct nvkm_pstate, which is an out-of-bounds read. [Francesco: rebased on drm-misc-next, expanded the commit message]
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Update the Linux kernel to 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9 or 7.3, depending on the kernel branch in use.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 7 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98623
- 2026-10-18 Alias added: GHSA-5c9q-m24x-7r34
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/db5dd9f47b4df1be322f498d846e9a82940a7390
- https://git.kernel.org/stable/c/9d550924961f61a491dd95359c63494fa8a23d9f
- https://git.kernel.org/stable/c/492e9cfa12f35f7946ea1b78a19f1f9337d62248
- https://git.kernel.org/stable/c/a867abcfa85ab487066c3d3008a1ba905da04113
- https://git.kernel.org/stable/c/5315c7bacfe274ddfe649d9556e9a341ffa812da
- https://git.kernel.org/stable/c/0d096a7f7d79207490858dde731b16da5337e90c
- https://git.kernel.org/stable/c/391517da7fd54ae40e4a7fe1cc696217343b0061
- https://git.kernel.org/stable/c/aff09d9e37e02dc60bde79035ac15b136d602259
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Sources
- CVE-2026-98623 · CVE Program
- CVE-2026-98623 · NVD
- FIRST EPSS
- GHSA-5c9q-m24x-7r34 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98623 · Red Hat security data · CC BY 4.0
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