CyberSecBulletin
CVE-2026-43133NVD status: Modified

Linux: Improper Check for Unusual or Exceptional Conditions

Published Updated By the CyberSecBulletin desk

CVE-2026-43133 is a high-severity improper check for unusual or exceptional conditions vulnerability in Linux, with a CVSS 3.1 base score of 7.9 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 10063e1251c1485034a018236080792ad083dcc5, c3b7015000988ba35ecd5648f4b2283960f00543, 3880e331b0b31d0d5d3702b124f6c93539cd478a as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 10063e1251c1485034a018236080792ad083dcc5 or c3b7015000988ba35ecd5648f4b2283960f00543 or 3880e331b0b31d0d5d3702b124f6c93539cd478a or fce2fd4a2ca05670a91015aacccf96a1c26268fd, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.202 or 6.1.165 or 6.6.128 or 6.12.75, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxcc3ed80ae69f454c3d904af9f65394a540099723 up to, but not including, 10063e1251c1485034a018236080792ad083dcc5; cc3ed80ae69f454c3d904af9f65394a540099723 up to, but not including, c3b7015000988ba35ecd5648f4b2283960f00543; cc3ed80ae69f454c3d904af9f65394a540099723 up to, but not including, 3880e331b0b31d0d5d3702b124f6c93539cd478a; cc3ed80ae69f454c3d904af9f65394a540099723 up to, but not including, fce2fd4a2ca05670a91015aacccf96a1c26268fd; cc3ed80ae69f454c3d904af9f65394a540099723 up to, but not including, d464cf1ed900d47c85393d40b00017b6adfc2e6c; cc3ed80ae69f454c3d904af9f65394a540099723 up to, but not including, 0004ecb798b30e90d7ebfe74efae2d9423315a64; cc3ed80ae69f454c3d904af9f65394a540099723 up to, but not including, 127ccae2c185f62e6ecb4bf24f9cb307e9b9c619; 5.1310063e1251c1485034a018236080792ad083dcc5, c3b7015000988ba35ecd5648f4b2283960f00543, 3880e331b0b31d0d5d3702b124f6c93539cd478a, fce2fd4a2ca05670a91015aacccf96a1c26268fd, d464cf1ed900d47c85393d40b00017b6adfc2e6c, 0004ecb798b30e90d7ebfe74efae2d9423315a64
Red HatRed Hat Enterprise Linux 10Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 6Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 7Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4Not specified in the recordNot stated
LinuxLinux Kernel5.13 up to, but not including, 5.15.202; 5.16 up to, but not including, 6.1.165; 6.2 up to, but not including, 6.6.128; 6.7 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.16; 6.19 up to, but not including, 6.19.65.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
LowSome restricted data can be read.
Integrity
LowLimited modification of data is possible.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H. Scored by CNA.

Scoring systemScoreSeverityScored by
CVSS 3.17.9HighCNA
CVSS 3.17.9HighCNA

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Check for Unusual or Exceptional Conditions

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Choose languages with features such as exception handling that force the programmer to anticipate unusual conditions that may generate exceptions. Custom exceptions may need to be developed to handle unusual business-logic conditions. Be careful not to pass sensitive exceptions back to the user (CWE-209, CWE-248).
  • Check the results of all functions that return a value and verify that the value is expected.
  • If using exception handling, catch and throw specific exceptions instead of overly-general exceptions (CWE-396, CWE-397). Catch and handle exceptions as locally as possible so that exceptions do not propagate too far up the call stack (CWE-705). Avoid unchecked or uncaught exceptions where feasible (CWE-248).

More Improper Check for Unusual or Exceptional Conditions vulnerabilities (CWE-754)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Check for Unusual or Exceptional Conditions vulnerabilities

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