CVE-2021-3623

vTPM crash via retained oversized buffer length

Published Mar 2, 2022 · Updated Aug 3, 2024

Out-of-bounds access in libtpms allows local users to crash a vTPM through crafted TPM 2 command packets containing illegal values. Failed TPM2B unmarshalling leaves illegal size values in memory, and TPMLIB_VolatileAll_Store later marshals them without a maximum-size check. Exploitation requires direct or indirect access to that API; the documented scope is limited to a crash or information leakage rather than code execution.

CVSS severity6.1
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Out-of-bounds access in libtpms allows local users to crash a vTPM through crafted TPM 2 command packets containing illegal values. Failed TPM2B unmarshalling leaves illegal size values in memory, and TPMLIB_VolatileAll_Store later marshals them without a maximum-size check. Exploitation requires direct or indirect access to that API; the documented scope is limited to a crash or information leakage rather than code execution.

The record

CVE
CVE-2021-3623
Published
Mar 2, 2022
Updated
Aug 3, 2024
Vendor
libtpms Project
Product
libtpms
Classifications
CWE-787, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 2, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed-In - libtpms 0.6.5, libtpms 0.7.8, libtpms 0.8.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

libtpms Project · libtpmsversion=Fixed-In - libtpms 0.6.5, libtpms 0.7.8, libtpms 0.8.4

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
3.6NIST NVDAV:L/AC:L/Au:N/C:P/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo