Security readout for executives and security teams
Plain-English summary
CVE-2021-47302 is a Linux kernel bug in the igc network driver. During a controller reset, the driver can touch already-freed network buffer memory, causing a use-after-free warning and possible system instability. The record does not provide CVSS, impact scoring, or evidence of active exploitation.
Executive priority
Treat as a targeted kernel reliability risk rather than a confirmed internet-wide emergency. Prioritize affected Linux infrastructure using the igc driver, especially operational technology or appliances where network instability has high business impact.
Technical view
The fix clears next_to_watch while cleaning the igc TX ring. Without that cleanup, igc_poll() racing with controller reset can attempt to free an skb already freed, producing refcount underflow and invalid memory access in kernel networking code.
Likely exposure
Exposure appears limited to Linux systems running affected kernel builds with the igc driver in use. The source lists affected Linux kernel versions including 4.20, 5.4.136, 5.10.54, 5.13.6, and 5.14; distro backports may alter practical exposure.
Exploitation context
The bundle does not cite public exploitation, weaponization, or CISA KEV inclusion. The trigger context is a reset race in the igc driver, so prioritize systems where this driver is loaded and network controller resets are operationally relevant.
Researcher notes
Evidence is strong for the bug and fix mechanics, but incomplete for exploitability and severity. The record gives kernel logs and stable commit references, but no CVSS, CWE, exploit status, or vendor-specific package matrix.
Mitigation direction
- Apply a vendor or distro kernel update containing the referenced stable fixes.
- Check Linux distribution advisories for backported fixes before judging by version string alone.
- Prioritize maintenance for systems where the igc driver is loaded.
- If no update is available, follow vendor guidance for temporary risk reduction.
Validation and detection
- Inventory Linux hosts and identify kernels with the igc driver loaded.
- Map installed kernel packages to distro advisories or the referenced stable commits.
- Review kernel logs for refcount underflow or use-after-free warnings involving igc_poll.
- After patching, verify normal network operation and absence of repeated igc reset warnings.
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
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CVE-2021-47302 mapping review
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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/a9508e0edfe369ac95d0825bcdca976436ce780fCVE reference, Linux
- https://git.kernel.org/stable/c/e15f629036bac005fc758b4ad17896cf2312add4CVE reference, Linux
- https://git.kernel.org/stable/c/ea5e36b7367ea0a36ef73a163768f16d2977bd83CVE reference, Linux
- https://git.kernel.org/stable/c/56ea7ed103b46970e171eb1c95916f393d64eeffCVE 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.