The GRUB2's shim_lock verifier allows non-kernel files to be loaded on shim-powered…
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 5 fixed, 1 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
The GRUB2's shim_lock verifier allows non-kernel files to be loaded on shim-powered secure boot systems. Allowing such files to be loaded may lead to unverified code and modules to be loaded in GRUB2 breaking the secure boot trust-chain.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA GNU GRUB (GNU Project) Fixed in 2.06-3
Red Hat 5 advisories
- RHSA-2022:5100 Released 2022-06-16 · Red Hat rating Importantgrub2, mokutil, shim, and shim-unsigned-x64 security update
- Red Hat CodeReady Linux Builder EUS (v. 8.2) shim-unsigned-x64-15.6-1.el8
- Red Hat Enterprise Linux BaseOS EUS (v. 8.2) grub2-1:2.02-87.el8_2.10, grub2-common-1:2.02-87.el8_2.10, grub2-efi-aa64-1:2.02-87.el8_2.10 +20
- RHSA-2022:5095 Released 2022-06-16 · Red Hat rating Importantgrub2, mokutil, shim, and shim-unsigned-x64 security update
- Red Hat Enterprise Linux BaseOS (v. 8) grub2-1:2.02-123.el8_6.8, grub2-common-1:2.02-123.el8_6.8, grub2-efi-aa64-1:2.02-123.el8_6.8 +20
- Red Hat Enterprise Linux CRB (v. 8) shim-unsigned-x64-15.6-1.el8
- RHSA-2022:5099 Released 2022-06-16 · Red Hat rating Importantgrub2, mokutil, shim, and shim-unsigned-x64 security update
- Red Hat CodeReady Linux Builder (v. 9) shim-unsigned-x64-15.6-1.el9
- Red Hat Enterprise Linux BaseOS (v. 9) grub2-1:2.06-27.el9_0.7, grub2-common-1:2.06-27.el9_0.7, grub2-efi-aa64-1:2.06-27.el9_0.7 +16
Show 2 more Red Hat advisories
- RHSA-2022:5096 Released 2022-06-16 · Red Hat rating Importantgrub2, mokutil, shim, and shim-unsigned-x64 security update
- Red Hat Enterprise Linux BaseOS EUS (v.8.4) grub2-1:2.02-99.el8_4.9, grub2-common-1:2.02-99.el8_4.9, grub2-efi-aa64-1:2.02-99.el8_4.9 +20
- Red Hat Enterprise Linux CRB EUS (v.8.4) shim-unsigned-x64-15.6-1.el8
- RHSA-2022:5098 Released 2022-06-16 · Red Hat rating Importantgrub2, mokutil, and shim security update
- Red Hat Enterprise Linux BaseOS E4S (v. 8.1) grub2-1:2.02-87.el8_1.10, grub2-common-1:2.02-87.el8_1.10, grub2-efi-aa64-modules-1:2.02-87.el8_1.10 +17
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
GNU GRUB 2.06-3
4 records Highest priority Priority MEDIUM 1 MEDIUM, 3 LOW
Other records, highest priority first
- TI-2022-11367 Integer underflow in GNU GRUBPriority MEDIUM 40
- TI-2022-11368 Out-of-bounds write in GNU GRUBPriority LOW 37
- TI-2022-11370 Use after free in GNU GRUBPriority LOW 36
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2022:5095 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2022:5099 |
| Red Hat Enterprise Linux BaseOS E4S (v. 8.1) | Fixed | RHSA-2022:5098 |
| Red Hat Enterprise Linux BaseOS EUS (v. 8.2) | Fixed | RHSA-2022:5100 |
| Red Hat Enterprise Linux BaseOS EUS (v.8.4) | Fixed | RHSA-2022:5096 |
Not affected: 9 products
- Red Hat CodeReady Linux Builder (v. 9)
- Red Hat CodeReady Linux Builder EUS (v. 8.2)
- Red Hat Enterprise Linux BaseOS (v. 8)
- Red Hat Enterprise Linux BaseOS (v. 9)
- Red Hat Enterprise Linux BaseOS E4S (v. 8.1)
- Red Hat Enterprise Linux BaseOS EUS (v. 8.2)
- Red Hat Enterprise Linux BaseOS EUS (v.8.4)
- Red Hat Enterprise Linux CRB (v. 8)
- Red Hat Enterprise Linux CRB EUS (v.8.4)
Timeline
- 2026-10-02 Threatist record created from CVE-2022-28735
- 2026-10-03 Alias added: GHSA-w8wh-9mrg-3ff5
References
More GNU Grub2 vulnerabilities
- TI-2023-04324 Grub2: out-of-bounds write at fs/ntfs.c may lead to unsigned code execution CVSS 3.1HIGH 7.8
- TI-2015-06891 Multiple integer underflows in Grub2 1.98 through 2.02 allow physically proximate… CVSS 3.1HIGH 7.4
- TI-2024-37620 Heap-based buffer overflow in GNU GRUB2 CVSS 3.1HIGH 8.8
- TI-2022-11367 Integer underflow in GNU GRUB CVSS 3.1HIGH 8.1
- TI-2022-02403 Heap-based buffer overflow in grub2 CVSS 3.1HIGH 8.6
- TI-2020-08612 Buffer overflow in Grub CVSS 3.1HIGH 8.2
Sources
- CVE-2022-28735 · CVE Program
- CVE-2022-28735 · NVD
- FIRST EPSS
- GHSA-w8wh-9mrg-3ff5 · GitHub Advisory Database · CC BY 4.0
- CVE-2022-28735 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences