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CVE Record

CVE-2021-47046: drm/amd/display: Fix off by one in hdmi_14_process_transaction()

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix off by one in hdmi_14_process_transaction() The hdcp_i2c_offsets[] array did not have an entry for HDCP_MESSAGE_ID_WRITE_CONTENT_STREAM_TYPE so it led to an off by one read overflow. I added an entry and copied the 0x0 value for the offset from similar code in drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c. I also declared several of these arrays as having HDCP_MESSAGE_ID_MAX entries. This doesn't change the code, but it's just a belt and suspenders approach to try future proof the code.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel AMD display driver bug. A missing table entry could make the driver read one item past an HDCP I2C offset array during HDMI HDCP message handling. Sources do not provide CVSS, impact details, or exploitation evidence, so urgency depends on affected kernel and AMD display usage.

Executive priority

Treat as a targeted kernel maintenance issue, not an emergency based on current evidence. Prioritize normal patch cycles for Linux fleets with AMD display exposure, and escalate only if vendor advisories add impact, exploitability, or severity details.

Technical view

CVE-2021-47046 fixes an off-by-one read overflow in hdmi_14_process_transaction() in drm/amd/display. hdcp_i2c_offsets[] lacked an entry for HDCP_MESSAGE_ID_WRITE_CONTENT_STREAM_TYPE. The upstream fix adds that entry and sizes related arrays against HDCP_MESSAGE_ID_MAX.

Likely exposure

Exposure appears limited to Linux systems using affected kernels with AMD display driver code paths. The provided data names Linux kernel versions or branches including 5.5, 5.10.37, 5.11.21, 5.12.4, and 5.13, but distribution backports require vendor-specific verification.

Exploitation context

The source bundle does not report active exploitation, public weaponization, or inclusion in CISA KEV. It describes a bounds read issue fixed in the Linux kernel, but does not establish practical attack conditions, privileges, or security impact beyond the overflow class.

Researcher notes

Evidence is sparse: no CVSS, CWE, impact statement, or exploit context is included. Analysis should stay anchored to the kernel fix: a missing HDCP message table entry caused an off-by-one read overflow, corrected by adding the missing offset and array sizing hardening.

Mitigation direction

  • Update affected Linux systems to a vendor kernel containing the referenced stable fixes.
  • Check distribution security advisories for backported fixes and package-specific version mapping.
  • Prioritize systems with AMD GPUs, HDMI output, or HDCP-dependent display workflows.
  • Track this as unresolved where kernel provenance cannot be confirmed.

Validation and detection

  • Inventory Linux kernel versions and AMD display hardware across endpoints and servers.
  • Map installed kernel packages to vendor advisories or the referenced stable commits.
  • Confirm whether drm/amd/display code is present and used on each target system.
  • Record systems with unknown kernel backport status for manual vendor verification.
Prepared
Confidence
medium
Sources
6

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

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CVE-2021-47046 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
2ADP providers
5Source 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
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4c283fdac08abf3211533f70623c90a34f41d08d, 4c283fdac08abf3211533f70623c90a34f41d08d, 4c283fdac08abf3211533f70623c90a34f41d08d, 4c283fdac08abf3211533f70623c90a34f41d08dunaffected
LinuxLinux5.5, 0, 5.10.37, 5.11.21, 5.12.4, 5.13affected
Weakness

CWE details

No CWE listed

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