CVE-2022-28736

Code execution via repeated EFI chainloader commands

Published Jul 20, 2023 · Updated Feb 13, 2025

Use-after-free in grub_cmd_chainloader() in GNU GRUB before 2.06-3 allows local users to execute code by invoking chainloader twice. The function stores an EFI image handle in shared global state, so replacing a pending loader unloads the new image while retaining its freed handle. Exploitation requires high privileges and control of GRUB's heap layout; successful use can expose sensitive data, execute code, and bypass Secure Boot protections.

CVSS severity6.4
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Use-after-free in grub_cmd_chainloader() in GNU GRUB before 2.06-3 allows local users to execute code by invoking chainloader twice. The function stores an EFI image handle in shared global state, so replacing a pending loader unloads the new image while retaining its freed handle. Exploitation requires high privileges and control of GRUB's heap layout; successful use can expose sensitive data, execute code, and bypass Secure Boot protections.

The record

CVE
CVE-2022-28736
Published
Jul 20, 2023
Updated
Feb 13, 2025
Vendor
The GnuPG Project
Product
GNU GRUB
Classifications
CWE-416, T1037
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jul 20, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=0 <2.06-3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The GnuPG Project · GNU GRUBversion=0 <2.06-3

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.4Canonical Ltd.CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1037Boot or Logon Autostart Execution: Boot or Logon Initialization Scripts

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo