CVE-2026-43133: Linux kernel · KVM: nSVM: Always use vmcb01 in VMLOAD/VMSAVE emulation
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.9 High · fixed in fce2fd4a2ca05670a91015aacccf96a1c26268fd : patch Linux kernel soon.
Data as of 26 Oct 2026, 10:24 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in fce2fd4a2ca05670a91015aacccf96a1c26268fd, d464cf1ed900d47c85393d40b00017b6adfc2e6c, c3b7015000988ba35ecd5648f4b2283960f00543 +4
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:HExploitation evidence
Disclosed: evidence found.
CVE published 6 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
In the Linux kernel, the following vulnerability has been resolved: KVM: nSVM: Always use vmcb01 in VMLOAD/VMSAVE emulation Commit cc3ed80ae69f ("KVM: nSVM: always use vmcb01 to for vmsave/vmload of guest state") made KVM always use vmcb01 for the fields controlled by VMSAVE/VMLOAD, but it missed updating the VMLOAD/VMSAVE emulation code to always use vmcb01. As a result, if VMSAVE/VMLOAD is executed by an L2 guest and is not intercepted by L1, KVM will mistakenly use vmcb02. Always use vmcb01 instead of the current VMCB.
References
- git.kernel.org/stable/c/10063e1251c1485034a018236080792ad083dcc5 (opens in a new tab)
- git.kernel.org/stable/c/c3b7015000988ba35ecd5648f4b2283960f00543 (opens in a new tab)
- git.kernel.org/stable/c/3880e331b0b31d0d5d3702b124f6c93539cd478a (opens in a new tab)
- git.kernel.org/stable/c/fce2fd4a2ca05670a91015aacccf96a1c26268fd (opens in a new tab)
- git.kernel.org/stable/c/d464cf1ed900d47c85393d40b00017b6adfc2e6c (opens in a new tab)
- git.kernel.org/stable/c/0004ecb798b30e90d7ebfe74efae2d9423315a64 (opens in a new tab)
- git.kernel.org/stable/c/127ccae2c185f62e6ecb4bf24f9cb307e9b9c619 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-43133 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2467065 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43133.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:66357 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65334 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:66180 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:67468 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:67469 (opens in a new tab)