CVE-2020-26933
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedTrusted Computing Group (TCG) Trusted Platform Module Library Family 2.0 Library Specification Revisions 1.38 through 1.59 has Incorrect Access Control during a non-orderly TPM shut-down that uses USE_DA_USED. Improper initialization of this shut-down may result in susceptibility to a dictionary attack.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceThe TPM 2.0 library specification versions 1.38-1.59 contain an incorrect access control vulnerability during non-orderly shutdowns that use the USE_DA_USED flag (Dictionary Attack protection). Improper initialization during this shutdown path can leave the TPM vulnerable to dictionary attacks, potentially allowing attackers to brute-force authentication secrets.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 2.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm TPM 2.0 hardware is presentOn Linux, run 'ls /dev/tpm*' or use 'tpm2_getcap -c'. On Windows, open Device Manager, expand 'Security devices', and check for TPM 2.0 compliant devices. Alternatively, run 'tpm.msc' to view TPM status.Affected if No TPM 2.0 device is detected or the TPM is version 1.2 only - the vulnerability only affects TPM 2.0 implementations.
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Retrieve TPM firmware versionUse vendor-specific tools (such as Intel TXT TXS, HP TPM Config Utility, or Dell TPM Firmware Update tools) or on Linux try 'tpm2_getcap -c properties-fixed' to query the TPM version. On Windows, the TPM Management console may display firmware version under 'TPM Manufacturer Information'.Affected if The displayed firmware version falls within the range 1.38 to 1.59 - these library specification versions contain the flaw.
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Check if TPM library version is exposedQuery the TPM using the TCG标准 tools: 'tpm2_getcap -c properties-fixed' on Linux or review vendor documentation for version reporting. Some systems expose the TPM library version separately from firmware version.Affected if The TPM library or specification version reported is between 1.38 and 1.59 inclusive.
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Identify dictionary attack protection configurationReview TPM DA (Dictionary Attack) protection settings. On Linux, use 'tpm2_getcap -c pcr-extend' or vendor management tools. Check if the system uses orderly shutdown or non-orderly shutdown configurations.Affected if Dictionary Attack (DA) protection is enabled and the system relies on non-orderly shutdown paths - the vulnerability specifically affects non-orderly shutdowns using the USE_DA_USED flag.
A system is affected if it contains a TPM 2.0 chip with firmware or library specification versions 1.38 through 1.59 and has Dictionary Attack protection configured for non-orderly shutdown scenarios.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataOrganizations should contact their TPM hardware vendors to obtain firmware updates that address this specification flaw, and ensure TPM-based systems are running vendor-supplied patches beyond library version 1.59.
- Consultation6.0 h
- Implementation12.0 h
- Testing10.0 h
- Review / QA6.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-26933 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-26933 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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