CVE-2021-33656

When setting font with malicous data by ioctl cmd PIO_FONT,kernel will write memory out of bounds.

Published: 2022-07-18 Last update: 2025-04-02 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-33656 is rated Low Risk (29.5/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-33656

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.21% 0.03% -0.18%
2 2025-11-18 0.01% 0.21% +0.20%
3 2025-03-17 — 0.01% —

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-33656

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.8 3.1 MEDIUM
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:P)
Hands-on access—USB, keyboard, opening the case—not something you do purely over the wire.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.9 5.9 [email protected]

Weakness enumeration for CVE-2021-33656

OS Trackers for CVE-2021-33656

vendor priority summary link
debian not yet assigned CVE-2021-33656 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-33656
redhat medium — https://access.redhat.com/security/cve/CVE-2021-33656
suse medium — https://www.suse.com/security/cve/CVE-2021-33656/
ubuntu medium CVE-2021-33656 medium priority: Ubuntu including 167 source packages (linux, linux-allwinner, …), 2042 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1576, released 202, not-affected 193, ignored 70, needed 1. https://ubuntu.com/security/CVE-2021-33656

Affected software / configurations for CVE-2021-33656

Vendor Product Version Raw CPE
openatom openeuler 20.03 cpe:2.3:o:openatom:openeuler:20.03:-:*:*:lts:*:*:*
openatom openeuler 20.03 cpe:2.3:o:openatom:openeuler:20.03:sp1:*:*:lts:*:*:*
openatom openeuler 20.03 cpe:2.3:o:openatom:openeuler:20.03:sp3:*:*:lts:*:*:*
linux linux_kernel < 5.10.127 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2021-33656

cvelogic Threat Intelligence