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Fencer Vulns
medium 6.3

CVE-2020-8918 json

TPM 1.2 key authorization values are vulnerable to a TPM transport eavesdropper

published 2020-08-11 6 y ago modified 2026-07-08 4 mo ago also GHSA-5x29-3hr9-6wpw , GO-2021-0095 , EUVD-2022-0847

cvss
6.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

An improperly initialized 'migrationAuth' value in Google's go-tpm TPM1.2 library versions prior to 0.3.0 can lead an eavesdropping attacker to discover the auth value for a key created with CreateWrapKey. An attacker listening in on the channel can collect both 'encUsageAuth' and 'encMigrationAuth', and then can calculate 'usageAuth ^ encMigrationAuth' as the 'migrationAuth' can be guessed for all keys created with CreateWrapKey. TPM2.0 is not impacted by this. We recommend updating your library to 0.3.0 or later, or, if you cannot update, to call CreateWrapKey with a random 20-byte value for 'migrationAuth'.

Patch / fix

  • go github.com/google/go-tpm 0.3.0
  • Google LLC google/go-tpm library 0.3.0

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/google/go-tpm/security/advisories/GHSA-5x29-3hr9-6wpw referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.3 CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
NVD 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
NVD 2.0 3.6 AV:L/AC:L/Au:N/C:P/I:P/A:N
GitHub 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
go github.com/google/go-tpm
<0.3.0
0.3.0

Affected products

  • Google LLC google/go-tpm library

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.