# CVE-2026-90303: linux: In the Linux kernel, the following vulnerability has been resolved:  ARM: 9485/1: mm: acquire mmap write lock around...

CVE-2026-90303 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-90303, released September 23, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-90303
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0022
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 17, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults  When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set, a user fault may trigger show_pte() without any lock. If another thread in the same process concurrently calls munmap(), the page table pages may be freed while show_pte() is still traversing them, causing a use-after-free in show_pte().  If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table of PMD are freed when show_pte() is running.  Acquire mmap_write_lock() around show_pte() for user faults to fix the contention.  For user faults, additionally restrict that show_pte() is called only when the addr is a user-space address (addr < TASK_SIZE). This is because the lock of tsk->mm only protects the virtual memory of user address space, furthermore, dumping the page tables of a kernel-space address for user faults is unnecessary and may have security implications.  Keep everything unchanged for kernel faults, because the kernel is already in the "oops" state, acquiring a lock may risk a deadlock.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.190-1 | [DEBIAN-CVE-2026-90303](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90303.md) | Sep 23, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.111-1 | [DEBIAN-CVE-2026-90303](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90303.md) | Sep 23, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-90303](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90303.md) | Sep 23, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.111-1~deb12u1 | [DEBIAN-CVE-2026-90303](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90303.md) | Sep 23, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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