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CVE Record

CVE-2025-71077: tpm: Cap the number of PCR banks

In the Linux kernel, the following vulnerability has been resolved: tpm: Cap the number of PCR banks tpm2_get_pcr_allocation() does not cap any upper limit for the number of banks. Cap the limit to eight banks so that out of bounds values coming from external I/O cause on only limited harm.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue is in TPM handling. The kernel did not cap how many TPM PCR banks it would accept, so abnormal values from external TPM I/O could drive out-of-bounds behavior. The public bundle does not provide CVSS, impact detail, or evidence of exploitation.

Executive priority

Treat this as a routine kernel maintenance item unless your environment depends heavily on TPM2 assurance workflows. There is no cited exploitation or severity score, but kernel memory-safety issues should not be left untracked.

Technical view

tpm2_get_pcr_allocation() lacked an upper bound for PCR bank count. The fix caps the number of PCR banks at eight, limiting harm from out-of-bounds values received through external I/O. References are Linux stable commits; affected version details in the bundle are limited and should be confirmed per distribution.

Likely exposure

Exposure is likely limited to Linux systems using TPM2 functionality where the kernel processes PCR bank allocation data. The bundle identifies Linux kernel as affected, but does not provide deployment-specific reachability or distribution package status.

Exploitation context

No active exploitation is stated. The bundle says KEV is false and provides no public exploit evidence. The described trigger depends on malformed or out-of-bounds TPM-related input from external I/O, but no attack path is detailed.

Researcher notes

The key detail is missing bounds checking in tpm2_get_pcr_allocation(), corrected by capping PCR banks at eight. Source evidence does not establish exploitability, privileges required, crash behavior, or confidentiality/integrity impact.

Mitigation direction

  • Apply Linux kernel updates that include the referenced stable fixes.
  • Check your Linux distribution advisory for packaged fixed versions.
  • Prioritize systems relying on TPM2, measured boot, or attestation workflows.
  • Track vendor guidance because no separate workaround is named in the bundle.

Validation and detection

  • Inventory Linux kernel versions across TPM-capable systems.
  • Confirm whether vendor kernels include one of the referenced stable commits.
  • Review distribution CVE advisories for CVE-2025-71077 status.
  • Validate TPM2-dependent hosts after kernel update deployment.
Prepared
Confidence
medium
Sources
9

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2025-71077 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
1ADP providers
8Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxbcfff8384f6c4e6627676ef07ccad9cfacd67849, bcfff8384f6c4e6627676ef07ccad9cfacd67849, bcfff8384f6c4e6627676ef07ccad9cfacd67849, bcfff8384f6c4e6627676ef07ccad9cfacd67849, bcfff8384f6c4e6627676ef07ccad9cfacd67849, bcfff8384f6c4e6627676ef07ccad9cfacd67849, bcfff8384f6c4e6627676ef07ccad9cfacd67849unaffected
LinuxLinux5.1, 0, 5.10.248, 5.15.198, 6.1.160, 6.6.120, 6.12.64, 6.18.3, 6.19affected
Weakness

CWE details

No CWE listed

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