CVE-2026-43109

Local kernel crash via unchecked mmap lock

Published May 6, 2026 · Updated May 6, 2026

Improper error handling in Linux Kernel x86 shadow stacks allows local users to crash the kernel during signal-frame return. The shstk_pop_sigframe() path ignores an error returned by mmap_read_lock_killable() and continues as though the memory-map lock were held. Exploitation requires low-privileged local code, a page-aligned shadow-stack pointer, and interrupted lock acquisition; the bounded consequence is a kernel crash.

CVSS severity5.5
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper error handling in Linux Kernel x86 shadow stacks allows local users to crash the kernel during signal-frame return. The shstk_pop_sigframe() path ignores an error returned by mmap_read_lock_killable() and continues as though the memory-map lock were held. Exploitation requires low-privileged local code, a page-aligned shadow-stack pointer, and interrupted lock acquisition; the bounded consequence is a kernel crash.

The record

CVE
CVE-2026-43109
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <262b6d38a81d51b135db81e1f30c13d30e38feee
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <52f657e34d7b21b47434d9d8b26fa7f6778b63a0
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c64cebcc5c4f223dbcbe7dcdf74908fc092a0aa4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <262b6d38a81d51b135db81e1f30c13d30e38feee; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <52f657e34d7b21b47434d9d8b26fa7f6778b63a0; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c64cebcc5c4f223dbcbe7dcdf74908fc092a0aa4

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
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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Your stack

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