CVE-2021-46927

Kernel crash via unlocked enclave memory mapping

Published Feb 27, 2024 · Updated May 11, 2026

Improper locking in Linux 5.15 through 5.15.12 allows local users to crash the kernel through a Nitro Enclaves memory-region ioctl. ne_set_user_memory_region_ioctl calls get_user_pages without holding mmap_lock; find_vma enforces the lock assertion and triggers a kernel BUG. Reachability requires local low-privileged access to the primary EC2 VM and an enabled Nitro Enclaves driver; the documented consequence is a host-kernel crash.

CVSS severity5.5
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in Linux 5.15 through 5.15.12 allows local users to crash the kernel through a Nitro Enclaves memory-region ioctl. ne_set_user_memory_region_ioctl calls get_user_pages without holding mmap_lock; find_vma enforces the lock assertion and triggers a kernel BUG. Reachability requires local low-privileged access to the primary EC2 VM and an enabled Nitro Enclaves driver; the documented consequence is a host-kernel crash.

The record

CVE
CVE-2021-46927
Published
Feb 27, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=5.15
  2. Affected versionversion=5b78ed24e8ec48602c1d6f5a188e58d000c81e2b <3a0152b219523227c2a62a0a122cf99608287176
  3. Affected versionversion=5b78ed24e8ec48602c1d6f5a188e58d000c81e2b <90d2beed5e753805c5eab656b8d48257638fe543

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.15; version=5b78ed24e8ec48602c1d6f5a188e58d000c81e2b <3a0152b219523227c2a62a0a122cf99608287176; version=5b78ed24e8ec48602c1d6f5a188e58d000c81e2b <90d2beed5e753805c5eab656b8d48257638fe543

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.

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

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

CWE-667Improper Locking
T1499Endpoint Denial of Service

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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