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CVE Record

CVE-2026-64048: net/smc: reject CHID-0 ACCEPT that matches an empty ism_dev slot

In the Linux kernel, the following vulnerability has been resolved: net/smc: reject CHID-0 ACCEPT that matches an empty ism_dev slot On the SMC-D client, slot 0 of ini->ism_dev[]/ini->ism_chid[] is reserved for an SMC-Dv1 device. smc_find_ism_v2_device_clnt() populates V2 entries starting at index 1, so when no V1 device is selected slot 0 is left in its kzalloc()'ed state with ism_dev[0] == NULL and ism_chid[0] == 0. smc_v2_determine_accepted_chid() then matches the peer's CHID against the array starting from index 0 using the CHID alone. A malicious peer replying to a SMC-Dv2-only proposal with d1.chid == 0 matches the empty slot, ini->ism_selected becomes 0, and the subsequent ism_dev[0]->lgr_lock dereference in smc_conn_create() faults at offsetof(struct smcd_dev, lgr_lock) == 0x68: BUG: KASAN: null-ptr-deref in _raw_spin_lock_bh+0x79/0xe0 Write of size 4 at addr 0000000000000068 by task exploit/144 Call Trace: _raw_spin_lock_bh smc_conn_create (net/smc/smc_core.c:1997) __smc_connect (net/smc/af_smc.c:1447) smc_connect (net/smc/af_smc.c:1720) __sys_connect __x64_sys_connect do_syscall_64 Require ism_dev[i] to be non-NULL before accepting a CHID match.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This Linux kernel flaw can let a malicious network peer crash an affected system by triggering a null pointer dereference in the SMC-D connection path. The impact described is availability loss, not data theft or privilege escalation. Active exploitation is not established in the provided sources.

Executive priority

Treat as high priority for exposed Linux infrastructure because a remote unauthenticated peer may cause a kernel crash. Patch during the next urgent maintenance window, with faster action for systems relying on SMC-D.

Technical view

In net/smc, an SMC-Dv2-only client can accept peer CHID 0 because matching checks CHID before verifying ism_dev[i] is non-NULL. That selects empty slot 0, leading to a NULL dereference at smc_conn_create() when lgr_lock is accessed. The fix requires a non-NULL ism_dev before accepting the CHID match.

Likely exposure

Exposure is likely limited to Linux systems with affected kernel versions and reachable SMC-D/AF_SMC functionality. The source lists Linux as affected across several kernel version ranges, but distribution package mappings are not provided.

Exploitation context

CVSS is 7.5 with network attack vector, low complexity, no privileges, and high availability impact. KEV is false, and the supplied sources do not state in-the-wild exploitation or a public weaponized exploit.

Researcher notes

The key condition is CHID 0 matching an empty reserved slot on SMC-D clients. The remediation changes acceptance logic, not authentication. The bundle does not include CWE mapping, distro status, exploit publication, or non-Linux affected products.

Mitigation direction

  • Apply a Linux kernel update containing the referenced stable fixes.
  • Check distribution advisories for package versions mapping to these commits.
  • Prioritize hosts using SMC-D or AF_SMC network functionality.
  • If no package exists, follow vendor guidance for temporary exposure reduction.

Validation and detection

  • Inventory Linux kernel versions against the affected ranges in the CVE bundle.
  • Confirm whether SMC-D or AF_SMC functionality is enabled on relevant hosts.
  • Verify installed kernel packages include the vendor backport or stable fix.
  • Review monitoring for kernel crash or null-dereference events in net/smc paths.
Prepared
Confidence
high
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.

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CVE-2026-64048 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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
7Source 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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-64048Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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
LinuxLinuxa7c9c5f4af7f6098da68705fc5d86565d0728ef7, a7c9c5f4af7f6098da68705fc5d86565d0728ef7, a7c9c5f4af7f6098da68705fc5d86565d0728ef7, a7c9c5f4af7f6098da68705fc5d86565d0728ef7, a7c9c5f4af7f6098da68705fc5d86565d0728ef7, a7c9c5f4af7f6098da68705fc5d86565d0728ef7unaffected
LinuxLinux5.10, 0, 6.1.175, 6.6.142, 6.12.92, 6.18.34, 7.0.11, 7.1affected
Weakness

CWE details

No CWE listed

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