Cyber Resilience

CVE-2021-42554

High

Published: 03 February 2022

Published
03 February 2022
Modified
04 November 2025
KEV Added
Patch
CVSS Score v3.1 8.2 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.0009 26.1th percentile
Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-42554 is a high-severity Out-of-bounds Write (CWE-787) vulnerability in Insyde Insydeh2O. Its CVSS base score is 8.2 (High).

Operationally, ranked at the 26.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

An issue was discovered in Insyde InsydeH2O with Kernel 5.0 before 05.08.42, Kernel 5.1 before 05.16.42, Kernel 5.2 before 05.26.42, Kernel 5.3 before 05.35.42, Kernel 5.4 before 05.42.51, and Kernel 5.5 before 05.50.51. An SMM memory corruption vulnerability in FvbServicesRuntimeDxe…

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allows a possible attacker to write fixed or predictable data to SMRAM. Exploiting this issue could lead to escalating privileges to SMM.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

insyde
insydeh2o
5.0 — 5.08.42 · 5.1 — 5.16.42 · 5.2 — 5.26.42
siemens
simatic field pg m5 firmware
all versions
siemens
simatic field pg m6 firmware
all versions
siemens
simatic ipc127e firmware
all versions
siemens
simatic ipc227g firmware
all versions
siemens
simatic ipc277g firmware
all versions
siemens
simatic ipc327g firmware
all versions
siemens
simatic ipc377g firmware
all versions
siemens
simatic ipc427e firmware
all versions
siemens
simatic ipc477e firmware
all versions
+6 more product configuration(s) — see NVD for full list

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-787

Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.

References