# CVE-2026-90046: mm/page_alloc: don't spin_trylock() in NMI on UP

CVE-2026-90046 is fixed in linux on 1 platform by DEBIAN-CVE-2026-90046 (version 7.2.6-1), released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-90046
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 16, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-90046

## Description

In the Linux kernel, the following vulnerability has been resolved:  mm/page_alloc: don't spin_trylock() in NMI on UP  Patch series "mm/page_alloc: fixes for free_pages_nolock() on RT/UP".  Pre-existing bugs found by Sashiko during review of this other series: https://lore.kernel.org/all/20260703-alloc-trylock-v5-0-c87b714e19d3@google.com/  I have not reproduced these bugs, and I suspect there is no real-world user that is affected by them.   This patch (of 2):  As noted in can_spin_trylock(), using this is unsafe in this context.  commit 620b46ed6ae17 ("mm/page_alloc: return NULL early from alloc_frozen_pages_nolock() in NMI on UP") fixed this on the alloc side but missed the free side.  Impact: If BPF programs using these features in NMI (probably tracing) are present on non-SMP builds this might crash the kernel and is probably exploitable by local attackers for privilege escalation.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-90046](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90046.md) | Sep 23, 2026 |

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