Security readout for executives and security teams
Plain-English summary
A Linux KVM defect on arm64 can calculate the wrong memory address while swapping virtualization descriptors. The supplied CVSS assessment indicates that a locally authenticated, low-privilege attacker could potentially cause serious confidentiality, integrity, and availability impact. The source bundle does not describe demonstrated exploitation or specific real-world outcomes.
Executive priority
Treat this as a high-priority maintenance issue for arm64 KVM infrastructure, especially where less-trusted users or workloads have local access. Accelerate vendor-supported kernel updates, but avoid declaring an emergency solely from CVSS: the supplied evidence does not establish active exploitation or quantify practical reachability.
Technical view
In __kvm_at_swap_desc(), adding offset to a u64 user pointer scaled the offset by eight. The intended address was the host virtual address plus the byte offset. This could select an incorrect Stage-1 or Stage-2 descriptor address during swapping. Referenced stable-kernel commits correct the pointer arithmetic.
Likely exposure
Exposure appears limited to arm64 Linux systems using the affected KVM functionality. The bundle identifies the Linux 6.19 line as affected, but does not clearly map every fixed release or distribution backport. Non-arm64 systems and hosts not using KVM are less likely to reach this code path.
Exploitation context
The CVSS vector indicates local access, low complexity, low privileges, no user interaction, and possible cross-scope impact. CISA KEV status is false in the supplied bundle, and no cited source reports active exploitation, public proof-of-concept availability, or a confirmed attack chain.
Researcher notes
The root cause is incorrect typed-pointer arithmetic: offset was multiplied by sizeof(u64) instead of treated as a byte offset. The bundle provides no CWE, reproducer, crash trace, affected configuration details, or exploitability analysis. Researchers should verify reachability and fixed-version mappings without assuming the CVSS worst-case impacts are demonstrated.
Mitigation direction
- Apply a vendor-supported kernel containing the referenced stable fix.
- Check distribution advisories for backported fixes and corrected package versions.
- Prioritize arm64 virtualization hosts running Linux 6.19-series kernels.
- Restrict untrusted local access to affected virtualization hosts until remediated.
Validation and detection
- Inventory arm64 hosts, running kernel versions, and KVM usage.
- Compare installed kernels with vendor advisories and referenced stable commits.
- Confirm the corrected kernel is running after maintenance or reboot.
- Review host telemetry for unexplained KVM failures or memory-related crashes.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CVE-2026-31553 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H26LinuxVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/4307e05e568782fc92eff651b09ee5dee88a058dCVE reference, Linux
- https://git.kernel.org/stable/c/0496acc42fb51eee040b5170cec05cec41385540CVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.