CVE-2021-20233
Setparam_prefix() in the menu rendering code performs a length calculation on the assumption that expressing a quoted single quote will require 3 characters, while it actually requires 4 characters which allows an attacker to corrupt memory by one byte…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.60%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
A flaw was found in grub2 in versions prior to 2.06. Setparam_prefix() in the menu rendering code performs a length calculation on the assumption that expressing a quoted single quote will require 3 characters, while it actually requires 4 characters which allows an attacker to corrupt memory by one byte for each quote in the input. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
- CVSS 3.1
- 8.2 HIGHCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
- EPSS
- 0.60% probability · 49th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-787
- Affected
- gnu/grub2 · redhat/enterprise linux · redhat/enterprise linux server aus · redhat/enterprise linux server eus · redhat/enterprise linux server tus · redhat/enterprise linux workstation · fedoraproject/fedora · netapp/ontap select deploy administration utility
- Source
- secalert@redhat.com
EPSS 0.6% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.redhat.com/show_bug.cgi?id=1926263Issue Tracking, Patch, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZWZ36QK4IKU6MWDWNOOWKPH3WXZBHT2R/
- https://security.gentoo.org/glsa/202104-05Third Party Advisory
- https://security.netapp.com/advisory/ntap-20220325-0001/Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1926263Issue Tracking, Patch, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZWZ36QK4IKU6MWDWNOOWKPH3WXZBHT2R/
- https://security.gentoo.org/glsa/202104-05Third Party Advisory
- https://security.netapp.com/advisory/ntap-20220325-0001/Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.