CVE-2020-5953

A vulnerability exists in System Management Interrupt (SWSMI) handler of InsydeH2O UEFI Firmware code located in SWSMI handler that dereferences gRT (EFI_RUNTIME_SERVICES) pointer to call a GetVariable service, which is located outside of SMRAM. This can result in code execution in SMM (escalating privilege from ring 0 to ring -2).

Published: 2022-02-02 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-5953 is rated Low Risk (36.8/100): CVSS High severity, with low exploitation likelihood (EPSS 0.27%). 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-2020-5953

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 2026-06-15 0.07% 0.27% +0.21%
2 2026-04-10 0.29% 0.07% -0.23%
3 2025-11-21 — 0.29% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-5953

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
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.
 0.8 6.0 [email protected]
6.9 2.0 MEDIUM
AV:L/AC:M/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.4 10.0 [email protected]

Weakness enumeration for CVE-2020-5953

Affected software / configurations for CVE-2020-5953

Vendor Product Version Raw CPE
insyde insydeh2o 5.12.09.0074 cpe:2.3:a:insyde:insydeh2o:5.12.09.0074:*:*:*:*:*:*:*
insyde insydeh2o 5.23.04.0045 cpe:2.3:a:insyde:insydeh2o:5.23.04.0045:*:*:*:*:*:*:*
insyde insydeh2o 5.23.45.0023 cpe:2.3:a:insyde:insydeh2o:5.23.45.0023:*:*:*:*:*:*:*
insyde insydeh2o 5.33.15.0034 cpe:2.3:a:insyde:insydeh2o:5.33.15.0034:*:*:*:*:*:*:*
insyde insydeh2o 5.34.03.0029 cpe:2.3:a:insyde:insydeh2o:5.34.03.0029:*:*:*:*:*:*:*
insyde insydeh2o 5.42.03.0010 cpe:2.3:a:insyde:insydeh2o:5.42.03.0010:*:*:*:*:*:*:*
siemens ruggedcom_ape1808_firmware — cpe:2.3:o:siemens:ruggedcom_ape1808_firmware:-:*:*:*:*:*:*:*
siemens simatic_field_pg_m6_firmware — cpe:2.3:o:siemens:simatic_field_pg_m6_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc127e_firmware — cpe:2.3:o:siemens:simatic_ipc127e_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc227g_firmware — cpe:2.3:o:siemens:simatic_ipc227g_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc277g_firmware — cpe:2.3:o:siemens:simatic_ipc277g_firmware:-:*:*:*:*:*:*:*
siemens simatic_itp1000_firmware — cpe:2.3:o:siemens:simatic_itp1000_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc477e_pro_firmware — cpe:2.3:o:siemens:simatic_ipc477e_pro_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc627e_firmware — cpe:2.3:o:siemens:simatic_ipc627e_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc647e_firmware — cpe:2.3:o:siemens:simatic_ipc647e_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc677e_firmware — cpe:2.3:o:siemens:simatic_ipc677e_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc847e_firmware — cpe:2.3:o:siemens:simatic_ipc847e_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc327g_firmware — cpe:2.3:o:siemens:simatic_ipc327g_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc377g_firmware — cpe:2.3:o:siemens:simatic_ipc377g_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc427e_firmware — cpe:2.3:o:siemens:simatic_ipc427e_firmware:-:*:*:*:*:*:*:*
siemens simatic_ipc477e_firmware — cpe:2.3:o:siemens:simatic_ipc477e_firmware:-:*:*:*:*:*:*:*
siemens simatic_field_pg_m5_firmware — cpe:2.3:o:siemens:simatic_field_pg_m5_firmware:-:*:*:*:*:*:*:*

References for CVE-2020-5953

cvelogic Threat Intelligence