Description
In arch/x86/kvm/vmx.c in the Linux kernel before 4.17.2, when nested virtualization is used, local attackers could cause L1 KVM guests to VMEXIT, potentially allowing privilege escalations and denial of service attacks due to lack of checking of CPL.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 4.16.16-1 | — |
| Debian 13 | linux | 4.16.16-1 | — |
| Debian 12 | linux | 4.16.16-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | linux | 4.15.0-33.36 | USN-3752-1 |
| Ubuntu 18.04 LTS | linux-aws +1 | 4.15.0-1020.20 | USN-3752-1 |
| Ubuntu 18.04 LTS | linux-azure | 4.15.0-1022.23 | USN-3752-3 |
| Ubuntu 18.04 LTS | linux-gcp | 4.15.0-1018.19 | USN-3752-1 |
| Ubuntu 18.04 LTS | linux-oem | 4.15.0-1017.20 | USN-3752-3 |
| Ubuntu 18.04 LTS | linux-raspi2 | 4.15.0-1021.23 | USN-3752-1 |
| Ubuntu 16.04 LTS | linux-azure | 4.15.0-1022.22~16.04.1 | USN-3752-3 |
| Ubuntu 16.04 LTS | linux-gcp | 4.15.0-1018.19~16.04.2 | USN-3752-3 |
| Ubuntu 16.04 LTS | linux-hwe | 4.15.0-33.36~16.04.1 | USN-3752-2 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLE Live Patching 15 | kernel-livepatch-SLE15_Update_0 | 2-4.1 | SUSE-SU-2018:2474-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Exploit-DB 1
- KVM (Nested Virtualization) - L1 Guest Privilege Escalation EDB-44944 · dos · Jun 25, 2018 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 4
- USN-3752-1 linux, linux-aws, linux-gcp, linux-kvm, linux-raspi2 vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- USN-3752-3 linux-azure, linux-oem, linux-gcp vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- USN-3752-2 linux-hwe vulnerabilities Ubuntu Security Notices (USN) · Jun 3, 2026
- SUSE-SU-2018:2474-1 Security update for the Linux Kernel (Live Patch 0 for SLE 15) SUSE / openSUSE Security Updates · Feb 4, 2026
References
- USN-3752-2 vendor-advisory
- https://github.com/torvalds/linux/commit/727ba748e110b4de50d142edca9d6a9b7e6111d8
- USN-3752-3 vendor-advisory
- https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.17.2
- https://bugs.chromium.org/p/project-zero/issues/detail?id=1589
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=727ba748e110b4de50d142edca9d6a9b7e6111d8
- USN-3752-1 vendor-advisory
- 44944 exploit