CVE-2026-31553
Published: 24 April 2026
Summary
CVE-2026-31553 is a high-severity an unspecified weakness vulnerability in Linux Linux Kernel. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 2.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and RA-5 (Vulnerability Monitoring and Scanning).
Deeper analysis
CVE-2026-31553 affects the Linux kernel's KVM implementation on arm64 architectures. The vulnerability resides in the __kvm_at_swap_desc() function, where virtual addresses for S1/S2 descriptors were incorrectly calculated using "(u64 __user *)hva + offset". This results in hva + offset*8 instead of the intended hva + offset when the offset is non-zero, potentially leading to improper descriptor swapping.
A local attacker with low privileges can exploit this issue with low attack complexity and no user interaction required. Exploitation grants high impacts on confidentiality, integrity, and availability with a changed scope, as reflected in the CVSS v3.1 base score of 8.8 (AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H).
Mitigation is provided through patches in the Linux kernel stable repository. Relevant commits include 0496acc42fb51eee040b5170cec05cec41385540 and 4307e05e568782fc92eff651b09ee5dee88a058d, which correct the descriptor address computation in __kvm_at_swap_desc(). Systems running affected kernel versions should apply these updates promptly.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-25446
Vulnerability details
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Fix the descriptor address in __kvm_at_swap_desc() Using "(u64 __user *)hva + offset" to get the virtual addresses of S1/S2 descriptors looks really wrong, if offset is not zero.…
more
What we want to get for swapping is hva + offset, not hva + offset*8. ;-) Fix it.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
KVM arm64 memory corruption bug (descriptor address miscalculation) allows local low-priv exploitation with scope change, directly enabling privilege escalation and VM-to-host escape.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires identifying, prioritizing, testing, and deploying patches to fix kernel flaws like the incorrect descriptor address calculation in KVM's __kvm_at_swap_desc().
Vulnerability scanning detects systems running Linux kernel versions vulnerable to CVE-2026-31553 in the KVM arm64 implementation.
Receives and disseminates security alerts and directives to enable timely patching of KVM kernel vulnerabilities like this descriptor swapping error.