CVE-2026-23346: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-23346 is a type confusion vulnerability (CWE-843) in the Linux kernel's arm64 ioremap_prot() function that allows local low-privilege users to trigger kernel panics and denial of service on systems with Privileged Access Never (PAN) enabled. The flaw was disclosed on March 25, 2026, and affects Linux kernel versions 6.0.1 through 6.18.16, 6.19.0 through 6.19.6, and early 7.0 release candidates (rc1–rc7). It carries a CVSS v3.1 base score of 5.5 (Medium) (Red Hat Advisory, Red Hat Bugzilla).

The root cause is that ioremap_prot() on arm64 incorrectly uses the full pgprot_t value — which includes user-space permission bits — when creating kernel memory mappings via generic_access_phys(). Because pgprot_t on arm64 encodes all non-address bits from the page table entry (including access permission controls), the resulting kernel mapping retains user-space permissions and faults when the kernel attempts to read from it on PAN-enabled systems, producing an "Unable to handle kernel read from unreadable memory" panic (CWE-843: Access of Resource Using Incompatible Type). The fix extracts only the memory type from the user pgprot_t and adds an assertion that a user mapping is being passed, while introducing a dedicated ioremap() macro wrapping __ioremap_prot() to avoid false positives (Red Hat Bugzilla, Kernel Patch 1).

Exploitation causes a kernel panic ("Unable to handle kernel read from unreadable memory") on arm64 systems with PAN enabled, resulting in a denial of service (system crash). The attack can be triggered by a local user with low privileges performing operations that invoke generic_access_phys(), such as reading /proc/[pid]/environ. There is no confidentiality or integrity impact — the vulnerability is limited to availability (Red Hat Advisory).

1. Identify target: Confirm the target system is running an arm64 Linux kernel between versions 6.0.1–6.18.16 or 6.19.0–6.19.6 (or 7.0-rc1 through rc7) with PAN (Privileged Access Never) enabled.
2. Obtain local access: Gain a local shell with low-privilege user credentials on the target system.
3. Trigger the vulnerable code path: Execute a read operation against /proc/[pid]/environ for a process whose memory-mapped regions include device/physical memory (e.g., a process using mmap() on a device file), which causes the kernel to invoke environ_read() → access_remote_vm() → generic_access_phys() → ioremap_prot().
4. Cause kernel panic: The kernel attempts to read from the improperly mapped memory region (user-permission mapping used in kernel context), triggering an "Unable to handle kernel read from unreadable memory" fault and crashing the system (Red Hat Bugzilla).

• Logs: Kernel panic messages containing "Unable to handle kernel read from unreadable memory at virtual address" in /var/log/kern.log or dmesg output; call traces referencing __memcpy_fromio, generic_access_phys, __access_remote_vm, environ_read, and ksys_read.
• System Behavior: Unexpected system reboots or kernel oops events on arm64 hosts; repeated crashes correlated with /proc/[pid]/environ read operations.
• Process: Unusual or repeated access to /proc/*/environ by low-privilege users, particularly for processes with device-backed memory mappings.

Upgrade the Linux kernel to version 6.18.17 or later, 6.19.7 or later, or 7.0-rc2 or later, which contain the fix. Specific upstream patch commits are 3d64dcc0799c2d6921ba027716b7be721eb19fa8, 8f098037139b294050053123ab2bc0f819d08932, and d1ad8fe7f72d73e1617bac79f2ec7a3bedf47e2a. Distribution-specific updates are available from Red Hat, SUSE (SUSE-SU-202621834-1, SUSE-SU-20262217-1, SUSE-SU-20262238-1), Amazon Linux 2023 (ALAS2023-2026-1596), and openSUSE. As a temporary workaround, restrict low-privilege user access to /proc operations and limit use of device-backed memory mappings until patching is complete (Red Hat Advisory, SUSE Advisory, Amazon Linux Advisory).

Red Hat tracked the issue via Bugzilla (Bug 2451236) and published a security advisory shortly after disclosure. SUSE issued multiple security updates (SUSE-SU-202621834-1, SUSE-SU-20262217-1, SUSE-SU-20262238-1) addressing the vulnerability. Amazon Linux 2023 also released a patch advisory (ALAS2023-2026-1596). The Yocto Project security mailing list flagged the CVE for embedded Linux maintainers. No significant independent researcher commentary or social media discussion has been observed beyond standard vendor patch notifications (Red Hat Bugzilla, SUSE Advisory).