VulnerabilityPublished 19 Jul 2026

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

Source GCVE Database

Authoritative record:CVE-2026-64048· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in dd2f9dd83c68abd7ba7ded7075290b016cb7ecd0 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in dd2f9dd83c68abd7ba7ded7075290b016cb7ecd0, d38ba387244e5c5f7db3e11ea98bc2c7beccb0c0, afa9036b8c9963947b487c36e332df6a42c96fcb +5

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-942p-vjp4-xm8p

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a7c9c5f4af7f6098da68705fc5d86565d0728ef7, < dd2f9dd83c68abd7ba7ded7075290b016cb7ecd0	Fixed in dd2f9dd83c68abd7ba7ded7075290b016cb7ecd0
LinuxLinux	Affected ≥ a7c9c5f4af7f6098da68705fc5d86565d0728ef7, < d38ba387244e5c5f7db3e11ea98bc2c7beccb0c0	Fixed in d38ba387244e5c5f7db3e11ea98bc2c7beccb0c0
LinuxLinux	Affected ≥ a7c9c5f4af7f6098da68705fc5d86565d0728ef7, < afa9036b8c9963947b487c36e332df6a42c96fcb	Fixed in afa9036b8c9963947b487c36e332df6a42c96fcb
LinuxLinux	Affected ≥ a7c9c5f4af7f6098da68705fc5d86565d0728ef7, < 277740023def559a4a2ddc3e8e784ee37a0f16a9	Fixed in 277740023def559a4a2ddc3e8e784ee37a0f16a9
LinuxLinux	Affected ≥ a7c9c5f4af7f6098da68705fc5d86565d0728ef7, < 6927cacf2b10d4fa80c1a2d407512ef9397c59c6	Fixed in 6927cacf2b10d4fa80c1a2d407512ef9397c59c6
LinuxLinux	Affected ≥ a7c9c5f4af7f6098da68705fc5d86565d0728ef7, < 903f7688ffeb9b323d70652c01f554bd4ba2a3d6	Fixed in 903f7688ffeb9b323d70652c01f554bd4ba2a3d6

AI-suggested

A fix has been implemented in the Linux kernel to require ism_dev[i] to be non-NULL before accepting a CHID match, preventing the NULL pointer dereference. Users should apply the official kernel update that includes this patch. Patch status is not explicitly confirmed in the provided data; check the vendor advisory or Linux kernel mailing lists for the official fix and update guidance.

Description

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.

Impact

Successful exploitation causes a kernel NULL pointer dereference, resulting in a kernel crash (BUG) and denial of service. There is no indication of privilege escalation or arbitrary code execution from the provided data.

Summary

The Linux kernel vulnerability CVE-2026-64048 involves the net/smc subsystem where the function smc_v2_determine_accepted_chid() matches a peer's CHID against an array starting at index 0. Slot 0 is reserved for SMC-Dv1 devices and may be NULL if no such device is selected. A malicious peer sending a CHID of 0 can cause the kernel to accept this match, leading to a NULL pointer dereference when smc_conn_create() attempts to access ism_dev[0]->lgr_lock. The fix requires verifying that ism_dev[i] is non-NULL before accepting a CHID match, preventing the NULL dereference.

References

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