CVE-2026-90291

Local kernel memory access via RCU lifetime race

Published Sep 17, 2026 · Updated Sep 18, 2026

Use-after-free in Linux 6.4 and later affected branches allows local users to access freed kernel memory during module loading. kmod_dup_request_delete() frees a kmod_dup_req after synchronize_rcu(), while kmod_dup_request_exists_wait() retains it across a blocking modprobe wait without an RCU read-side critical section. Concurrent duplicate module requests and deletion during that wait are required, with no user interaction.

CVSS severity5.8
Medium
EPSS probability0.17%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux 6.4 and later affected branches allows local users to access freed kernel memory during module loading. kmod_dup_request_delete() frees a kmod_dup_req after synchronize_rcu(), while kmod_dup_request_exists_wait() retains it across a blocking modprobe wait without an RCU read-side critical section. Concurrent duplicate module requests and deletion during that wait are required, with no user interaction.

The record

CVE
CVE-2026-90291
Published
Sep 17, 2026
Updated
Sep 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 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=6.4
  2. Affected versionversion=8660484ed1cf3261e89e0bad94c6395597e87599 <2c85e0fb528e039aa8ea1e9c2a1f64347f990541
  3. Affected versionversion=8660484ed1cf3261e89e0bad94c6395597e87599 <5eecb11b543f9f417bcf0dea239ff99c6af65dbd
  4. Affected versionversion=8660484ed1cf3261e89e0bad94c6395597e87599 <b2709aad7599f6fd957939b60f4a8323c8f08072
  5. Affected versionversion=8660484ed1cf3261e89e0bad94c6395597e87599 <cd2396fc9684d2cfd3f3c3f09c79d6d9d725b0ca

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.4; version=8660484ed1cf3261e89e0bad94c6395597e87599 <2c85e0fb528e039aa8ea1e9c2a1f64347f990541; version=8660484ed1cf3261e89e0bad94c6395597e87599 <5eecb11b543f9f417bcf0dea239ff99c6af65dbd; version=8660484ed1cf3261e89e0bad94c6395597e87599 <b2709aad7599f6fd957939b60f4a8323c8f08072; version=8660484ed1cf3261e89e0bad94c6395597e87599 <cd2396fc9684d2cfd3f3c3f09c79d6d9d725b0ca

Published CVSS scores

5.8Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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