CVE-2025-21998

Kernel crash via premature efivars registration

Published Apr 3, 2025 · Updated May 11, 2026

A race condition in Linux allows local users to crash the kernel by racing EFI variable access during driver initialization. The Qualcomm UEFI secure-app driver registers efivars before its trusted-zone memory pool is allocated, so an early access dereferences a NULL pool pointer. Exploitation requires local low-privileged access and a Qualcomm platform using this driver; the resulting kernel failure interrupts the host.

CVSS severity4.7
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race condition in Linux allows local users to crash the kernel by racing EFI variable access during driver initialization. The Qualcomm UEFI secure-app driver registers efivars before its trusted-zone memory pool is allocated, so an early access dereferences a NULL pool pointer. Exploitation requires local low-privileged access and a Qualcomm platform using this driver; the resulting kernel failure interrupts the host.

The record

CVE
CVE-2025-21998
Published
Apr 3, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, CWE-367, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 3, 2025CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=6.11
  2. Affected versionversion=6612103ec35af6058bb85ab24dae28e119b3c055 <c4e37b381a7a243c298a4858fc0a5a74e737c79a
  3. Affected versionversion=6612103ec35af6058bb85ab24dae28e119b3c055 <da8d493a80993972c427002684d0742560f3be4a
  4. Affected versionversion=6612103ec35af6058bb85ab24dae28e119b3c055 <f15a2b96a0e41c426c63a932d0e63cde7b9784aa

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.11; version=6612103ec35af6058bb85ab24dae28e119b3c055 <c4e37b381a7a243c298a4858fc0a5a74e737c79a; version=6612103ec35af6058bb85ab24dae28e119b3c055 <da8d493a80993972c427002684d0742560f3be4a; version=6612103ec35af6058bb85ab24dae28e119b3c055 <f15a2b96a0e41c426c63a932d0e63cde7b9784aa

Published CVSS scores

4.7NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7CISA-ADPCVSS:3.1/AV:L/AC:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
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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