CVE-2026-99258

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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.

CVSS — (—)

Attention and evidence

HYPE SCORE

0.0/10

REALITY · THREAT PRIORITY

0.0–3.5/10

Missing inputs: range of priority

Evidence confidence: Insufficient evidence

Why this priority?

Fresh EPSS: 0.19%: +0.00

Technical severity unavailable

General review priority, not probability, victim count or asset-specific risk. A range covers missing CVSS/EPSS inputs within the current evidence state.

Based on public data to date.

Hype components

Headline sample (25%)

0/100

Press, 30 days (60%)

0/100

Grounded branding (15%)

0/100

HYPE TOTAL0/100

Sources and documents

No source documents yet.

Score evolution

● Hype ● Reality

First record: hype 0.0 · reality 0.0 (2026-11-04 13:51). The curve appears once the score changes.

Public exploit evidence

Public exploit entries / repo candidates

Evidence context and dated references

Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs. Published 4 days ago. Exploitation evidence usually takes weeks to show up: a low reality score can mean there is no data yet, not that the flaw is mild.

Evidence in context

Confidence in exploitation evidence: Insufficient evidence
Priority basis: Exploitation in attacks unconfirmed; severity unavailable; EPSS 0.2%
Attention, last 30 days: 0 distinct story titles; 0 press documents; 0 publisher domains.
Technical potential: Not available as a validated CVSS vector..
Observed activity: No exploitation observation is recorded.
Known scale: Not quantified.
Evidence confidence basis: Insufficient evidence

Score evaluated: 2026-11-05 14:00:34.806270+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline

Published

03 Nov 2026, 11:25

Score calculated

05 Nov 2026, 14:00