CVE-2026-97991

Guest-to-host memory read and write via sector underflow

Published Sep 25, 2026 · Updated Sep 25, 2026

Out-of-bounds access in the Linux vdpa_sim_blk driver allows guest OS users to read or overwrite host memory via crafted block requests. vdpasim_blk_check_range() logs an out-of-range start but continues, allowing an unsigned capacity subtraction to underflow before IN, OUT, and WRITE_ZEROES use blk->buffer + offset. Exploitation requires access to a configured vDPA simulator block device; reads can disclose adjacent host memory, while writes can corrupt it and interrupt the host.

CVSS severityUnavailable
Unscored
EPSS probability0.12%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds access in the Linux vdpa_sim_blk driver allows guest OS users to read or overwrite host memory via crafted block requests. vdpasim_blk_check_range() logs an out-of-range start but continues, allowing an unsigned capacity subtraction to underflow before IN, OUT, and WRITE_ZEROES use blk->buffer + offset. Exploitation requires access to a configured vDPA simulator block device; reads can disclose adjacent host memory, while writes can corrupt it and interrupt the host.

The record

CVE
CVE-2026-97991
Published
Sep 25, 2026
Updated
Sep 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.13
  2. Affected versionversion=7d189f617f83f780915b737896a696ff605bd19f <0a8693f00c408d85f086ad85d29e7030bf1e2055
  3. Affected versionversion=7d189f617f83f780915b737896a696ff605bd19f <14acb0d44b7d90a077beb7b92b444b90bafda9d9
  4. Affected versionversion=7d189f617f83f780915b737896a696ff605bd19f <a8a1413a2cfdbedc896249f461d6d92efbbfe21f
  5. Affected versionversion=7d189f617f83f780915b737896a696ff605bd19f <d6dac17e20fd2abd0eb8c09d69fccf7426e12bcf

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.13; version=7d189f617f83f780915b737896a696ff605bd19f <0a8693f00c408d85f086ad85d29e7030bf1e2055; version=7d189f617f83f780915b737896a696ff605bd19f <14acb0d44b7d90a077beb7b92b444b90bafda9d9; version=7d189f617f83f780915b737896a696ff605bd19f <a8a1413a2cfdbedc896249f461d6d92efbbfe21f; version=7d189f617f83f780915b737896a696ff605bd19f <d6dac17e20fd2abd0eb8c09d69fccf7426e12bcf

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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