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CVE-2021-38578

31
FAUCET Score

CVE-2021-38578 is a critical vulnerability affecting Insyde and TianoCore EDK2 implementations, stemming from an integer underflow in SmmEntryPoint's CommBuffer size calculation. With a CVSS score of 9.8, it allows unauthenticated attackers to achieve high impact on confidentiality, integrity, and availability over the network with low attack complexity. While no public exploit code or active exploitation has been confirmed, the vulnerability has garnered some community discussion, indicating awareness within the cybersecurity community.

Impacted Technologies

VendorProductVersion(s)CPE
<= 202202CPE matchmatch criteria
cpe:2.3:a:tianocore:edk2:*:*:*:*:*:*:*:*
5.0CPE matchmatch criteria
cpe:2.3:o:insyde:kernel:5.0:*:*:*:*:*:*:*
5.1CPE matchmatch criteria
cpe:2.3:o:insyde:kernel:5.1:*:*:*:*:*:*:*
5.2CPE matchmatch criteria
cpe:2.3:o:insyde:kernel:5.2:*:*:*:*:*:*:*
5.3CPE matchmatch criteria
cpe:2.3:o:insyde:kernel:5.3:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.4HIGH

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:L

Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
HIGH
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
LOW
Exploitability Score
0.8
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.01%
Probability of exploitation in next 30 days
EPSS Percentile
59.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0101 is in the 44th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: edk2-0:20221207gitfff6d81270b5-9.el9_2
View patch
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: edk2

Vendor Advisories (2)

microsoft2022-Mar/CVE-2021-38578Important

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

Mar 8, 2022
redhatCVE-2021-38578Moderate

edk2: integer underflow in SmmEntryPoint function leads to potential SMM privilege escalation

Mar 3, 2022

References

lists.debian.org / debian-lts-announce/2025/06/msg00007.html
bugzilla.tianocore.org / show_bug.cgi
Issue TrackingVendor Advisory
insyde.com / security-pledge/SA-2023024
Third Party Advisory