HOMEVULNERABILITIESCVE-2021-33626
HIGH

CVE-2021-33626

CWE-829Published: October 1, 2021· Updated: Jun 17, 2026

7.8
CVSS v3.1

Official Description

A vulnerability exists in SMM (System Management Mode) branch that registers a SWSMI handler that does not sufficiently check or validate the allocated buffer pointer(QWORD values for CommBuffer). This can be used by an attacker to corrupt data in SMRAM memory and even lead to arbitrary code execution.

NVD Source

Technical Analysis

CVE-2021-33626 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 7.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

insyde1 product(s)
insydeh2o
siemens32 product(s)
ruggedcom apr1808 firmwareruggedcom apr1808simatic field pg m5 firmwaresimatic field pg m5simatic field pg m6 firmwaresimatic field pg m6simatic ipc127e firmwaresimatic ipc127esimatic ipc227g firmwaresimatic ipc227gsimatic ipc277g firmwaresimatic ipc277g+20
Source: NVD CPE · 33 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
ADVISORYhttps://security.netapp.com/advisory/ntap-20220216-0006/
ADVISORYhttps://www.insyde.com/security-pledge
ADVISORYhttps://www.insyde.com/security-pledge/SA-2021001
ADVISORYhttps://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
ADVISORYhttps://security.netapp.com/advisory/ntap-20220216-0006/
ADVISORYhttps://www.insyde.com/security-pledge
ADVISORYhttps://www.insyde.com/security-pledge/SA-2021001

All References (9)

→
https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdfThird Party Advisory
→
https://security.netapp.com/advisory/ntap-20220216-0006/Third Party Advisory
→
https://www.insyde.com/security-pledgeVendor Advisory
→
https://www.insyde.com/security-pledge/SA-2021001Vendor Advisory
→
https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdfThird Party Advisory
→
https://security.netapp.com/advisory/ntap-20220216-0006/Third Party Advisory
→
https://www.insyde.com/security-pledgeVendor Advisory
→
https://www.insyde.com/security-pledge/SA-2021001Vendor Advisory
→
https://www.kb.cert.org/vuls/id/796611

Quick Facts

CVE IDCVE-2021-33626
CVSS Score7.8 / 10
SeverityHIGH
WeaknessCWE-829
CISA KEVNo
Affected2 vendor(s)
PublishedOct 1, 2021

Related CVEs (CWE-829)

CVE-2020-4561
10.0
CVE-2025-0982
10.0
CVE-2026-27941
9.9
CVE-2012-4919
9.8
CVE-2019-13589
9.8
CVE-2025-59828
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-33626 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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