# CVE-2026-3842: Qemu-kvm: hyperv/syndbg: missing mapped-length guard after cpu_physical_memory_map causes host oob write

CVE-2026-3842 is fixed in 25 products on 1 platform, first by qemu-block-extra 1:8.2.2+ds-0ubuntu1.16, released April 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-3842
- Priority: High
- CVSS: 7.8 (Important)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 19, 2026
- Weakness: Out-of-bounds Write
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-3842

## Description

A flaw was found in QEMU. This vulnerability allows a local attacker within a guest virtual machine to write data beyond its allocated memory. This occurs when cpu_physical_memory_map() returns a shorter length than expected, leading to an out-of-bounds write. Successful exploitation could result in unauthorized access to guest memory or corruption of heap-allocated objects, potentially causing information disclosure, data integrity issues, or a denial of service.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | qemu Debian 13.5 (trixie) | 1:10.0.10+ds-0+deb13u1 | [DEBIAN-CVE-2026-3842](https://patchblox.com/security/data/fix/linux/debian-cve-2026-3842.md) | Jul 18, 2026 |
| Linux | qemu Debian 14 | 1:10.2.2+ds-1 | [DEBIAN-CVE-2026-3842](https://patchblox.com/security/data/fix/linux/debian-cve-2026-3842.md) | Jul 18, 2026 |
| Linux | qemu sles 15.6 | 8.2.10-150600.3.49.1 | [SUSE-SU-2026:2386-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2386-1.md) | Jun 12, 2026 |
| Linux | qemu sles 15.7 | 7.1.0-150500.49.42.1 | [SUSE-SU-2026:2388-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2388-1.md) | Jun 12, 2026 |
| Linux | qemu-block-extra Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-block-extra 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-block-extra-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-block-extra Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-block-extra 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-block-extra-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-block-supplemental Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-block-supplemental 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-block-supplemental-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-block-supplemental Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-block-supplemental 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-block-supplemental-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-guest-agent Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-guest-agent 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-guest-agent-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-guest-agent Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-guest-agent 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-guest-agent-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-linux-user sles 15.7 | 9.2.4-150700.3.20.1 | [SUSE-SU-2026:2385-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2385-1.md) | Jun 12, 2026 |
| Linux | qemu-system Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-arm Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-arm 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-arm-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-arm Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-arm 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-arm-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-common Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-common 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-common-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-common Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-common 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-common-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-data Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-data 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-data-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-data Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-data 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-data-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-gui Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-gui 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-gui-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-gui Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-gui 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-gui-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-mips Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-mips 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-mips-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-mips Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-mips 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-mips-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-misc Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-misc 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-misc-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-misc Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-misc 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-misc-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-modules-opengl Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-modules-opengl 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-modules-opengl-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-modules-opengl Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-modules-opengl 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-modules-opengl-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-modules-spice Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-modules-spice 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-modules-spice-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-modules-spice Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-modules-spice 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-modules-spice-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-ppc Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-ppc 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-ppc-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-ppc Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-ppc 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-ppc-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-riscv Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-riscv 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-riscv-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-s390x Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-s390x 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-s390x-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-s390x Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-s390x 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-s390x-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-sparc Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-sparc 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-sparc-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-sparc Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-sparc 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-sparc-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-x86 Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-x86 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-x86-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-x86 Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-x86 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-x86-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-x86-xen Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-x86-xen 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-x86-xen-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-x86-xen Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-x86-xen 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-x86-xen-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-system-xen Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-system-xen 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-system-xen-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-system-xen Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-system-xen 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-system-xen-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-user Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-user 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-user-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-user Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-user 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-user-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-user-binfmt Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-user-binfmt 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-user-binfmt-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-user-binfmt Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-user-binfmt 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-user-binfmt-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |
| Linux | qemu-user-static Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-user-static 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-user-static-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-utils Ubuntu 24.04.5 LTS (noble) | 1:8.2.2+ds-0ubuntu1.16 | [qemu-utils 1:8.2.2+ds-0ubuntu1.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-qemu-utils-1-8.2.2-ds-0ubuntu1.16.md) | Apr 15, 2026 |
| Linux | qemu-utils Ubuntu 25.10 (questing) | 1:10.1.0+ds-5ubuntu2.6 | [qemu-utils 1:10.1.0+ds-5ubuntu2.6](https://patchblox.com/security/data/fix/linux/ubuntu-questing-qemu-utils-1-10.1.0-ds-5ubuntu2.6.md) | Apr 15, 2026 |

---

Data as of 2026-11-08T19:12:23Z 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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