Home/CVE/Existing CommBuffer checks in SmmEntryPoint will not catch underflow when computing BufferSize.
CVE

CVE-2021-38578

Existing CommBuffer checks in SmmEntryPoint will not catch underflow when computing BufferSize.

Existing CommBuffer checks in SmmEntryPoint will not catch underflow when computing BufferSize.

HIGH · CVSS 7.4 EPSS 0.00064
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules8 YARA rules0
⬡

Weakness Classification

CWE-124Buffer Underwrite ('Buffer Underflow')
CWE-787Out-of-bounds Write
▤

Affected Products & Versions

2
tianocore edk2<= 202202
insyde kernelall versions
◈

Sigma Hunt Rules

8
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighLoading of Kernel Module via Insmod
producthighLiveKD Kernel Memory Dump File Created
producthighKernel Memory Dump Via LiveKD
producthighSuspicious Kernel Dump Using Dtrace
producthighPUA - Kernel Driver Utility (KDU) Execution
producthighCodeIntegrity - Revoked Kernel Driver Loaded
▣

Scoring & Timeline

7.4
HIGH · CVSS v3.1 · infosec@edk2.groups.io
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD03 Mar 2022 · 10:15 PM
CVSS VectorCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:L
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

12
msrcCVE-2021-38578
usnUSN-7060-1
suse-csafopenSUSE-SU-2024:12542-1
siemens-csafSSA-957369
suse-csafSUSE-SU-2023:2234-1
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://bugzilla.tianocore.org/show_bug.cgi?id=3387Issue TrackingVendor Advisory
https://www.insyde.com/security-pledge/SA-2023024Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/06/msg00007.html
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