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CVE Record

CVE-2021-47301: igb: Fix use-after-free error during reset

In the Linux kernel, the following vulnerability has been resolved: igb: Fix use-after-free error during reset Cleans the next descriptor to watch (next_to_watch) when cleaning the TX ring. Failure to do so can cause invalid memory accesses. If igb_poll() runs while the controller is reset this can lead to the driver try to free a skb that was already freed. (The crash is harder to reproduce with the igb driver, but the same potential problem exists as the code is identical to igc)

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47301 is a Linux kernel igb network driver memory safety bug. During a network controller reset, the driver can try to free network packet memory that was already freed, causing invalid memory access and likely kernel instability or crash on affected systems.

Executive priority

Handle through normal kernel patch management, with higher priority for production systems where network driver crashes would disrupt service. No supplied evidence supports emergency response for active exploitation.

Technical view

The igb driver did not clear the TX descriptor next_to_watch while cleaning the TX ring. If igb_poll() runs during controller reset, stale descriptor state can lead to freeing an already freed skb. The CVE record says the same potential problem existed as in igc because the code was identical.

Likely exposure

Exposure is likely limited to Linux systems using the affected igb Ethernet driver and vulnerable kernel versions. The source lists Linux kernel version ranges starting at 4.12 and stable fixes across multiple branches, but provides no asset-specific detection guidance.

Exploitation context

The bundle does not show active exploitation, public exploit use, or KEV listing. Evidence supports a race-like driver memory safety failure during reset, not a remotely proven attack path. Treat exploitability as unconfirmed from the supplied sources.

Researcher notes

The key condition is stale next_to_watch state in TX ring cleanup during controller reset. The source does not provide CVSS, CWE, exploitability analysis, or full distro impact mapping, so validation should stay tied to kernel branch and driver use.

Mitigation direction

  • Update affected Linux kernels to versions containing the referenced stable fixes.
  • Prioritize systems using Intel igb-backed network interfaces.
  • Check Linux vendor advisories for distribution-specific fixed kernel packages.
  • Schedule maintenance for network appliances or servers where kernel crashes affect availability.

Validation and detection

  • Inventory hosts using the Linux igb driver.
  • Confirm each host kernel version against vendor-fixed packages or referenced stable commits.
  • Review kernel logs for igb reset, skb, or invalid memory access crashes.
  • Verify patched hosts remain stable during normal network reset or maintenance events.
Prepared
Confidence
medium
Sources
8

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-2021-47301 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
7Source 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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux7cc6fd4c60f267e17b0baef1580d7a6258c0a6f0, 7cc6fd4c60f267e17b0baef1580d7a6258c0a6f0, 7cc6fd4c60f267e17b0baef1580d7a6258c0a6f0, 7cc6fd4c60f267e17b0baef1580d7a6258c0a6f0, 7cc6fd4c60f267e17b0baef1580d7a6258c0a6f0, 7cc6fd4c60f267e17b0baef1580d7a6258c0a6f0unaffected
LinuxLinux4.12, 0, 4.14.241, 4.19.199, 5.4.136, 5.10.54, 5.13.6, 5.14affected
Weakness

CWE details

No CWE listed

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