TPM 1.2 key authorization values vulnerable to TPM transport eavesdropper in go-tpm

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2020-8918: 0.18% estimated exploitation activity in the next 30 days; percentile 7.59 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact TPM 2.0 users are unaffected by this issue. An adversary eavesdropping on the TPM 1.2 transport path can calculate usageAuth for a key created with CreateWrapKey, even though this value is encrypted as part of the TPM 1.2 command protocol. The TPM 1.2 CreateWrapKey command accepts two secrets: usageAuth and migrationAuth. The ADIP protocol (TPM 1.2 specification, part 1, section 13.4) calls for these values to be encrypted with two different XOR keys. Due to a bug in go-tpm prior to version 0.3.0, both usageAuth and migrationAuth are encrypted with the same XOR keystream. This allows an adversary to XOR encUsageAuth and encMigrationAuth together to calculate usageAuth ^ encMigrationAuth. Since migrationAuth is moot for all keys created with go-tpm's CreateWrapKey (since all keys created with this function are marked non-migratable), an adversary may guess or know (from code/binary inspection) that migrationAuth is all 0x00 bytes or some other fixed value. Such an adversary can…

Published by the source

11 Feb 2022, 23:18 UTC

Last modified by the source

29 Aug 2023, 21:08 UTC

Source last checked

26 Oct 2026, 14:58 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5x29-3hr9-6wpw

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# Patch Next advisory brief: CVE-2020-8918

Advisory: TPM 1.2 key authorization values vulnerable to TPM transport eavesdropper in go-tpm
IDs: CVE-2020-8918, GHSA-5x29-3hr9-6wpw
Record: https://patchnext.com/advisories/cve-2020-8918 (revision 1, source checked 26 Oct 2026, 14:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/google/go-tpm 0.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/google/go-tpm: affected < 0.3.0; fixed in 0.3.0

## Suggested inspection (read-only)
- Go github.com/google/go-tpm: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/google/go-tpm.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5x29-3hr9-6wpw (GitHub-reviewed advisory GHSA-5x29-3hr9-6wpw lists affected ranges: Go github.com/google/go-tpm >=0 <0.3.0)

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