Security readout for executives and security teams
Plain-English summary
This is a Linux kernel driver bug in MediaTek mt7921 Wi-Fi support. The flaw could allow an array out-of-bounds access during transmit rate reporting. The public bundle confirms it was fixed in kernel stable commits, but gives no CVSS score or exploitation evidence.
Executive priority
Track and remediate through normal kernel update cycles unless asset inventory shows broad use of affected Wi-Fi hardware on sensitive systems. Escalate if a vendor advisory later reports exploitability or active abuse.
Technical view
CVE-2021-47135 affects the Linux kernel mt76 mt7921 driver function mt7921_mcu_tx_rate_report. The issue is described as a possible array out-of-bounds access. The bundle lists Linux 5.12, 5.12.10, and 5.13 in affected metadata and references two kernel stable fixes.
Likely exposure
Exposure is most likely on Linux systems running affected 5.12 or 5.13-era kernels with MediaTek MT7921 Wi-Fi hardware or the mt76/mt7921 driver present. The supplied data is not enough to confirm distro-specific package impact.
Exploitation context
No CISA KEV listing is provided and the source bundle contains no public exploitation claim. Treat this as a kernel memory-safety defect with uncertain exploitability, not as confirmed active exploitation.
Researcher notes
The public record is sparse: no CVSS, CWE, exploit status, or detailed impact is provided. Analysis should stay tied to the kernel commit references and local driver exposure rather than assuming remote code execution or broad Linux impact.
Mitigation direction
- Apply vendor kernel updates that include the referenced stable fixes.
- Check Linux distribution advisories for supported packages addressing CVE-2021-47135.
- Prioritize systems using mt76 or MediaTek MT7921 Wi-Fi support.
- Upgrade unsupported affected kernels to maintained vendor-supported releases.
Validation and detection
- Inventory kernel versions on Linux endpoints and appliances.
- Check whether mt76 or mt7921 driver support is present or loaded.
- Confirm installed kernel includes the referenced stable fix commits or vendor backports.
- Review distro security advisories for CVE mapping and package status.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-47135 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
SSVC decision data
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/6919e8a24e70b6ba148fe07f44f835bcdd1a8d02CVE reference, Linux
- https://git.kernel.org/stable/c/d874e6c06952382897d35bf4094193cd44ae91bdCVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.