# CVE-2022-26362: xen: x86 pv: Race condition in typeref acquisition Xen maintains a type reference count for pages, in addition to a regula...

CVE-2022-26362 is fixed in xen on 1 platform, first by DEBIAN-CVE-2022-26362, released June 9, 2022. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-26362
- Priority: Routine
- CVSS: 6.4 (medium)
- EPSS: 0.0039
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 9, 2022

## Description

x86 pv: Race condition in typeref acquisition Xen maintains a type reference count for pages, in addition to a regular reference count. This scheme is used to maintain invariants required for Xen's safety, e.g. PV guests may not have direct writeable access to pagetables; updates need auditing by Xen. Unfortunately, the logic for acquiring a type reference has a race condition, whereby a safely TLB flush is issued too early and creates a window where the guest can re-establish the read/write mapping before writeability is prohibited.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | xen Debian 12.15 (bookworm) | 4.16.2-1 | [DEBIAN-CVE-2022-26362](https://patchblox.com/security/data/fix/linux/debian-cve-2022-26362.md) | Jun 9, 2022 |
| Linux | xen Debian 13.5 (trixie) | 4.16.2-1 | [DEBIAN-CVE-2022-26362](https://patchblox.com/security/data/fix/linux/debian-cve-2022-26362.md) | Jun 9, 2022 |
| Linux | xen Debian 14 | 4.16.2-1 | [DEBIAN-CVE-2022-26362](https://patchblox.com/security/data/fix/linux/debian-cve-2022-26362.md) | Jun 9, 2022 |

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