CVE-2021-3418 — Improper Preservation of Permissions in Grub2

CWE-281 — Improper Preservation of Permissions7 documents7 sources
Severity
6.4MEDIUMNVD
EPSS
0.1%
top 79.35%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
1
GNU Grub2
Timeline
PublishedMar 15
Latest updateMay 24

Description

If certificates that signed grub are installed into db, grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown, yet it could have been tampered. This flaw is a reintroduction of CVE-2020-15705 and only affects grub2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism.

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:HExploitability: 0.5 | Impact: 5.9

Affected Packages2 packages

▶NVDgnu/grub2< 2.06
▶CVEListV5gnu/grub2Fixed in 2.06

🔴Vulnerability Details

3
GHSA
GHSA-j6wm-c7q8-jcx7: If certificates that signed grub are installed into db, grub can be booted directly↗2022-05-24
▶
CVEList
CVE-2021-3418: If certificates that signed grub are installed into db, grub can be booted directly↗2021-03-15
▶
OSV
CVE-2021-3418: If certificates that signed grub are installed into db, grub can be booted directly↗2021-03-15
▶

📋Vendor Advisories

3
Microsoft
If certificates that signed grub are installed into db grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot ↗2021-03-09
▶
Red Hat
grub2: grub 2.05 reintroduced CVE-2020-15705↗2021-03-02
▶
Debian
CVE-2021-3418: grub2 - If certificates that signed grub are installed into db, grub can be booted direc...↗2021
▶
CVE-2021-3418 — Improper Preservation of Permissions | cvebase