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MEDIUM

CVE-2026-17053

CVE-2026-17053 — SMBus callback-removal syscalls accept an unvalidated user pointer, letting user threads manipulate kernel callback state

The SMBus driver API exposed smbus_smbalert_remove_cb() and smbus_host_notify_remove_cb() as Zephyr syscalls. Their verifiers in drivers/smbus/smbus_handlers.c validated only the dev argument with K_SYSCALL_OBJ(dev, K_OBJ_DRIVER_SMBUS) and forwarded the caller-supplied struct smbus_callback *cb pointer into kernel-mode driver code without any K_SYSCALL_MEMORY_READ/K_SYSCALL_MEMORY_WRITE validation. A companion change in 2023 had already removed the matching smbus_smbalert_set_cb() / smbus_host_notify_set_cb() syscalls for this reason, but the two removal syscalls were left exposed. On a build with CONFIG_USERSPACE=y, CONFIG_SMBUS=y and a driver implementing the callback operations (drivers/smbus/intel_pch_smbus.c with CONFIG_SMBUS_INTEL_PCH_SMBALERT/CONFIG_SMBUS_INTEL_PCH_HOST_NOTIFY, or drivers/smbus/smbus_stm32.c with CONFIG_SMBUS_STM32_SMBALERT), any user-mode thread that has been…

Published Updated Sources: cvelistV5, zephyr

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

0%

chance of exploitation in 30 days

Affects

zephyrproject

zephyr

CVSS base

4.4

MEDIUM

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

No

can an attacker script all four kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (1)

zephyrproject

Products (1)

zephyr

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
4.4CVSS 3.1MEDIUM——cvelistV5

Weakness & attack patterns

  • CWE-862

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1211Exploitation for Defensive Evasion
  • T1542.002Pre-OS Boot: Component Firmware
  • T1556Modify Authentication Process

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

  • Search application, proxy, and WAF logs for requests touching /smbus/smbus_handlers.c, /K_SYSCALL_MEMORY_WRITE, /smbus/intel_pch_smbus.c, /CONFIG_SMBUS_INTEL_PCH_HOST_NOTIFY, /smbus/smbus_stm32.c.

References

2 on the record

Elsewhere on this site

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.