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CVE Record

CVE-2021-46991: i40e: Fix use-after-free in i40e_client_subtask()

In the Linux kernel, the following vulnerability has been resolved: i40e: Fix use-after-free in i40e_client_subtask() Currently the call to i40e_client_del_instance frees the object pf->cinst, however pf->cinst->lan_info is being accessed after the free. Fix this by adding the missing return. Addresses-Coverity: ("Read from pointer after free")

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 memory-safety bug in the i40e driver path. A freed object could be read afterward, which can cause reliability or security impact depending on reachability. The source bundle provides no CVSS score and no evidence of active exploitation.

Executive priority

Handle through normal kernel patch management unless critical i40e-dependent infrastructure is exposed or unstable. The lack of CVSS and exploit evidence limits urgency, but kernel memory-safety fixes should not be deferred indefinitely.

Technical view

CVE-2021-46991 fixes a use-after-free in i40e_client_subtask(). i40e_client_del_instance frees pf->cinst, then code accesses pf->cinst->lan_info. The fix adds a missing return to stop that post-free access. Affected Linux kernel version data is listed, with stable kernel commits referenced as fixes.

Likely exposure

Exposure is most relevant to Linux systems running affected kernel builds where the i40e driver code path is present. The bundle does not identify affected distributions, hardware requirements, privilege requirements, or remote reachability.

Exploitation context

The source bundle does not show CISA KEV listing, active exploitation, public exploit use, or weaponized details. Treat exploitation status as unconfirmed, not actively exploited.

Researcher notes

Evidence is limited to the CVE record and stable kernel commits. The root cause is a Coverity-identified read after free in i40e_client_subtask(). No exploitability analysis, attack vector, or distribution-specific fixed versions are included.

Mitigation direction

  • Update affected Linux kernels to packages containing the referenced stable fixes.
  • Check distribution advisories for CVE-2021-46991 backports and fixed package versions.
  • Prioritize hosts using or loading the i40e driver.
  • Follow vendor kernel guidance where exact fixed versions differ by distribution.

Validation and detection

  • Inventory Linux kernel versions across servers and appliances.
  • Identify systems where the i40e driver is present, configured, or loaded.
  • Review kernel package changelogs for CVE-2021-46991 or referenced commit IDs.
  • Confirm patched systems include the stable fix for i40e_client_subtask().
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-2021-46991 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

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux7b0b1a6d0ac983ce1928432285d0222d4fb7c38b, 7b0b1a6d0ac983ce1928432285d0222d4fb7c38b, 7b0b1a6d0ac983ce1928432285d0222d4fb7c38b, 7b0b1a6d0ac983ce1928432285d0222d4fb7c38b, 7b0b1a6d0ac983ce1928432285d0222d4fb7c38b, 7b0b1a6d0ac983ce1928432285d0222d4fb7c38bunaffected
LinuxLinux4.16, 0, 4.19.191, 5.4.120, 5.10.38, 5.11.22, 5.12.5, 5.13affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.