# CVE-2021-47255: linux: In the Linux kernel, the following vulnerability has been resolved:  kvm: LAPIC: Restore guard to prevent illegal API...

CVE-2021-47255 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47255, released May 21, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-47255
- Priority: High
- CVSS: 7.1 (high)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 21, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  kvm: LAPIC: Restore guard to prevent illegal APIC register access  Per the SDM, "any access that touches bytes 4 through 15 of an APIC register may cause undefined behavior and must not be executed." Worse, such an access in kvm_lapic_reg_read can result in a leak of kernel stack contents. Prior to commit 01402cf81051 ("kvm: LAPIC: write down valid APIC registers"), such an access was explicitly disallowed. Restore the guard that was removed in that commit.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.46-1 | [DEBIAN-CVE-2021-47255](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47255.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.46-1 | [DEBIAN-CVE-2021-47255](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47255.md) | May 21, 2024 |
| Linux | linux Debian 14 | 5.10.46-1 | [DEBIAN-CVE-2021-47255](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47255.md) | May 21, 2024 |

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