CVE-2026-90303 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN12-LINUX612-20506737
- published5 Oct 2026
- disclosed17 Sept 2026
Introduced: 17 Sep 2026
NewCVE-2026-90303 (opens in a new tab)How to fix?
Upgrade Debian:12 linux-6.12 to version 6.12.111-1~deb12u1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Debian.
See How to fix? for Debian:12 relevant fixed versions and status.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-90303
- https://git.kernel.org/stable/c/07e4d5380f2a844ab7a1b440dde350caf561cbb0
- https://git.kernel.org/stable/c/1039bffd6ae9c75b42b7d148d6c1106134107b66
- https://git.kernel.org/stable/c/2a14d7797a49a47bccd1a9327fd69da838dcb0dd
- https://git.kernel.org/stable/c/59bbf86d0ff9373bfa033ca123c1e924f09f1eba
- https://git.kernel.org/stable/c/63e3c958a602d0896a101a897c2361878c266ca7
- https://git.kernel.org/stable/c/720408d98d9fb3c91a12090436734c8c61f04545
- https://git.kernel.org/stable/c/ab14f07952adfe735d86a53518f8cd576dfd5892
- https://git.kernel.org/stable/c/c71f9a56520b419e55d173052629f2324deb5549