CVE-2026-99258
x86/hyperv: Avoid using per-cpu output page in hv_apicid_to_vp_index()
In the Linux kernel, the following vulnerability has been resolved: x86/hyperv: Avoid using per-cpu output page in hv_apicid_to_vp_index() hv_apicid_to_vp_index() currently uses the per-cpu hypercall input and output pages. This function is called when running in VTL2 and when running in an SEV-SNP CoCo VM with no paravisor. In the former case, the output page is allocated, but in the latter case it is not, so the hypervisor stores the output VP index in memory that has not been allocated by the guest. Fix this by using the input page for both input and output. The hypercall has very small input and output, so sharing the same page for both is straightforward. An alternative fix is to allocate the per-cpu output page when running in an SEV-SNP CoCo guest, but this uses significantly more memory, particularly with larger vCPUs counts.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ 3d12349ade541eefde0e71bf5c4aa7aa04c52a79; < bdba5f1b8bd0d18b1df61f769b559ed272902489 (affected, git) ≥ 86c48271e0d60c82665e9fd61277002391efcef7; < 2b561786c9076a892ef8b8f416c9828bc87ed44f (affected, git) ≥ 86c48271e0d60c82665e9fd61277002391efcef7; < bc8ca0f4769627ae7d04e7ffdbd20de4f27a9bf9 (affected, git) ≥ 86c48271e0d60c82665e9fd61277002391efcef7; < 7b74c117e2aac78e0f723e1c9c3644451c56b0d9 (affected, git) cb002d6c8f06d6061e84b2109cb84416107a9fb9 (affected, git) ≥ 6.12.41; < 6.12.115 (affected, semver) ≥ 6.15.3; < 6.16 (affected, semver) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
6.16 (affected) ≥ 0; < 6.16 (unaffected, semver) ≥ 6.12.115; ≤ 6.12.* (unaffected, semver) ≥ 6.18.59; ≤ 6.18.* (unaffected, semver) ≥ 7.2.13; ≤ 7.2.* (unaffected, semver) ≥ 7.3; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/bdba5f1b8bd0d18b1df61f769b559ed272902489CNA: Linux
- https://git.kernel.org/stable/c/2b561786c9076a892ef8b8f416c9828bc87ed44fCNA: Linux
- https://git.kernel.org/stable/c/bc8ca0f4769627ae7d04e7ffdbd20de4f27a9bf9CNA: Linux
- https://git.kernel.org/stable/c/7b74c117e2aac78e0f723e1c9c3644451c56b0d9CNA: Linux
For agents and automation
Read public disclosures for free as Markdown or JSON. Compatible browsers also expose native WebMCP tools to search disclosures, read this page, and discover API access.
Use the ontology-linked Cyber API with x402 pay per request, or a Y2 Pro or Elite API key with the intel:cyber scope.
Endpoints and access details
https://api.y2.dev/api/v2/cyber/cveshttps://api.y2.dev/api/v2/cyber/cves/{cveId}
A workspace owner or admin can create a Pro or Elite API key. Send Authorization: Bearer <Y2_API_KEY> from your trusted agent runtime.
For x402, omit Authorization and read the HTTP 402 payment challenge before signing a retry. Public browser tools do not make payments.