Security readout for executives and security teams
Plain-English summary
A malicious or compromised VIO server can cause a Linux system using ibmvfc to read beyond an allocated target list. Kernel memory may then be sent back to that server, exposing sensitive data and potentially affecting availability. Systems not using this virtual Fibre Channel path are unlikely to be exposed.
Executive priority
Prioritize affected ibmvfc environments, especially where VIO administration is shared or compromise could expose sensitive guest memory. Remediate promptly through supported kernel updates. Broad emergency action across Linux estates is unnecessary until teams confirm ibmvfc and VIO-backed storage are present.
Technical view
The ibmvfc discovery callback accepts num_written from a VIO-server MAD response without checking max_targets. ibmvfc_alloc_targets() then indexes beyond the DMA-coherent disc_buf allocation. Out-of-bounds kernel data can enter Implicit Logout and PLOGI MADs returned to the server. The fix clamps num_written to max_targets.
Likely exposure
Exposure is concentrated in Linux systems using the ibmvfc driver with VIO-provided virtual Fibre Channel. Exploitation requires control or compromise of the associated VIO server. The bundle provides upstream version and commit information, but not definitive distribution package boundaries; map deployed kernels through vendor advisories.
Exploitation context
The supplied bundle provides no evidence of active exploitation, and the CVE is not listed as KEV. The attacker must operate a malicious or compromised VIO server capable of returning an oversized discovery count. The supplied CVSS 3.1 score is 8.1, with adjacent access, low complexity, and no user interaction.
Researcher notes
The trust-boundary failure occurs when an untrusted response count becomes both stored state and a later array bound. Consequences documented in the bundle include out-of-bounds kernel access and disclosure through outbound MADs. Exact affected distribution builds, crash behavior, and real-world exploitation are not established by the supplied evidence.
Mitigation direction
- Inventory Linux systems using ibmvfc and VIO-backed virtual Fibre Channel storage.
- Apply a supported kernel update incorporating the referenced ibmvfc num_written validation fix.
- Consult distribution guidance to map deployed kernel packages to corrected builds.
Validation and detection
- Confirm whether ibmvfc is present and actively serving VIO-backed storage on each system.
- Compare the running kernel package with applicable distribution advisories and referenced stable fixes.
- Verify any source or backport clamps num_written to max_targets before setting num_targets.
- After remediation, confirm the corrected kernel build is the one currently running.
Public sources used
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2026-31464 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H2.85.2LinuxVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/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/d842348f8a00d5b1d7358f207eb34ffcf5b16df3CVE reference, Linux
- https://git.kernel.org/stable/c/a007246cb6c9ebdc93dafbf63cc2d43d98f402ccCVE reference, Linux
- https://git.kernel.org/stable/c/394a1cac3c12fdd7d77f19ccfd222ab5ff87ef89CVE reference, Linux
- https://git.kernel.org/stable/c/4ed727e35b0ab17d3eeeb1e8023768396e2be161CVE reference, Linux
- https://git.kernel.org/stable/c/d1466bf991b2343cf2ba8336e440c8faf3cbb780CVE reference, Linux
- https://git.kernel.org/stable/c/786f10b1966e485046839f992e89f2c18cbd1983CVE reference, Linux
- https://git.kernel.org/stable/c/bae4df0a643fa7f84663473aa3082a9c2ed139dbCVE reference, Linux
- https://git.kernel.org/stable/c/61d099ac4a7a8fb11ebdb6e2ec8d77f38e77362fCVE 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.