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CVE Record

CVE-2026-64056: net: ethernet: cortina: Make RX SKB per-port

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: cortina: Make RX SKB per-port The SKB used to assemble packets from fragments in gmac_rx() is static local, but the Gemini has two ethernet ports, meaning there can be races between the ports on a bad day if a device is using both. Make the RX SKB a per-port variable and carry it over between invocations in the port struct instead. Zero the pointer once we call napi_gro_frags(), on error (after calling napi_free_frags()) or if the port is stopped. Zero it in some place where not strictly necessary just to emphasize what is going on. This was found by Sashiko during normal patch review.

CriticalCVSS 9.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel driver flaw in the Cortina/Gemini Ethernet receive path. A shared packet buffer can race when both Ethernet ports are used, potentially affecting confidentiality, integrity, and availability. The CVE is rated critical, but exposure appears limited to systems using this specific driver and hardware path.

Executive priority

Treat as urgent for exposed embedded or network-facing Linux devices. For ordinary servers without this driver or hardware, priority is lower, but asset validation should happen quickly because the CVSS score is critical.

Technical view

In gmac_rx(), the receive SKB used to assemble packet fragments was a static local variable shared across Gemini’s two Ethernet ports. The fix makes the RX SKB per-port and clears it after GRO processing, error cleanup, or port stop conditions, reducing cross-port race risk.

Likely exposure

Most Linux systems are unlikely to be exposed unless they run an affected kernel with the Cortina/Gemini Ethernet driver and relevant dual-port hardware active. Embedded, network appliance, or vendor-custom Linux builds deserve priority review.

Exploitation context

The bundle lists KEV as false and provides no public evidence of active exploitation. The CVSS vector marks the issue network-reachable with no privileges or user interaction, but the source text does not describe a working exploit path.

Researcher notes

The source indicates a race in shared RX SKB state across two ports, discovered during normal patch review. Evidence does not include exploitability details, CWE mapping, or affected downstream distribution packages.

Mitigation direction

  • Update affected Linux kernels to a version containing the referenced stable fixes.
  • Prioritize embedded and network devices using Cortina/Gemini Ethernet hardware.
  • Check distribution or device-vendor advisories for packaged kernel fix availability.
  • Disable unused affected Ethernet ports where operationally acceptable until patched.

Validation and detection

  • Inventory systems using affected Linux kernel branches and Cortina/Gemini Ethernet hardware.
  • Confirm whether the Cortina/Gemini GMAC driver is built or loaded.
  • Verify the relevant stable commit is present in vendor kernel sources.
  • Review vendor advisories before treating generic upstream versions as definitive.
Prepared
Confidence
medium
Sources
10

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-2026-64056 mapping review

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

1CVSS vectors
3Timeline events
0ADP providers
9Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.8CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

9.8Critical
CVSS 3.1 vector shape for CVE-2026-64056Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88, 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88, 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88, 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88, 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88, 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88, 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88, 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88unaffected
LinuxLinux4.16, 0, 5.10.258, 5.15.209, 6.1.175, 6.6.142, 6.12.92, 6.18.34, 7.0.11, 7.1affected
Weakness

CWE details

No CWE listed

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