Spurious warning in arm64 ioremap_prot() for PROT_NONE mappings
Key facts
- Attack vector
- —
- Privileges required
- —
- User interaction
- —
- Attack complexity
- —
- Impact type
- —
- Confidentiality · integrity · availability
- —
- Fix status
- Fixed
No CVSS vector from any source. Fix status from CNA.
Summary
The Linux kernel on arm64 passes protection values without user access bits to ioremap_prot(), which triggers a spurious kernel warning. A local user can trigger it by mapping a process's stack-top page through /dev/mem with PROT_NONE and then reading that process's /proc/<pid>/cmdline. Execute-only mappings could also be read through the same path.
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: arm64: io: Reject non-user protection in ioremap_prot() Mapping a stack-top page via /dev/mem with PROT_NONE and then reading that process's /proc/<pid>/cmdline triggers a spurious WARN in ioremap_prot() through generic_access_phys(): WARNING: ./arch/arm64/include/asm/io.h:275 at generic_access_phys Call trace: generic_access_phys+0x1c8/0x228 (P) __access_remote_vm+0x2b4/0x398 access_remote_vm+0x14/0x30 get_mm_cmdline+0xf8/0x2a0 proc_pid_cmdline_read+0x68/0x120 generic_access_phys() passes the protection derived from the user PTE to ioremap_prot(). On arm64, a PROT_NONE mapping is represented by a present-invalid PTE, so pte_present() still returns true and the protection reaches ioremap_prot(). A PROT_NONE mapping does not have PTE_USER, causing the existing WARN_ON_ONCE() in ioremap_prot() to fire even though this is a valid user mapping. Execute-only mappings have the same issue and must not be readable through this path either. ioremap_prot() should therefore reject protection values without PTE_USER without warning. This makes the access fail cleanly for PROT_NONE and execute-only mappings while retaining the existing user-protection contract.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 6.6.143 to before 6.6.158; 6.12.93 to before 6.12.112; 6.18.17 to before 6.18.55; 6.19.7 to before 6.20 | 6.6.158, 6.12.112, 6.18.55, 6.20 | Patch available | CNA |
| Linux | Linux | 7.0 and later | 6.6.158, 6.12.112, 6.18.55, 7.2.9, 7.3 | Patch available | CNA |
- Linux VendorLinux Affected 6.6.143 to before 6.6.158; 6.12.93 to before 6.12.112; 6.18.17 to before 6.18.55; 6.19.7 to before 6.20 Fixed in 6.6.158, 6.12.112, 6.18.55, 6.20 Patch available CNA
- Linux VendorLinux Affected 7.0 and later Fixed in 6.6.158, 6.12.112, 6.18.55, 7.2.9, 7.3 Patch available CNA
Remediation
Update the Linux kernel to 6.6.158, 6.12.112, 6.18.55, 6.20, 7.2.9 or 7.3, which contain the fix.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 6.6.158, 6.12.112, 6.18.55, 6.20
- Fix · CNA Linux (Linux) Fixed in 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
- 2026-10-23 Threatist record created from CVE-2026-98923
- 2026-10-23 Alias added: GHSA-q3vh-mmhj-mxhr
- 2026-10-30 Affected versions changed · Red Hat
- 2026-10-30 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
Other 5
- https://git.kernel.org/stable/c/fddc90d4af4550af410f52d11bbf6b5f36443838
- https://git.kernel.org/stable/c/0b04af3d88bb7fc69b2d92457890608860e42365
- https://git.kernel.org/stable/c/b17aa4955e3a694c663ebe99626e4c76ca4f7cfb
- https://git.kernel.org/stable/c/9b583795feb51f8d50203228d001760d1344ef01
- https://git.kernel.org/stable/c/bb756b11ad63832ebee58caf9e8f9381eaecff9f
More Linux vulnerabilities
- TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
Sources
- CVE-2026-98923 · CVE Program
- CVE-2026-98923 · NVD
- FIRST EPSS
- GHSA-q3vh-mmhj-mxhr · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98923 · 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