CVE-2026-79976 zephyrproject CVE debrief

Who should care

Defenders responsible for Zephyr-based systems, particularly those using the MCTP I2C+GPIO target binding, should assess exposure and prioritize patching affected versions. This includes operators, platform administrators, vulnerability management teams, and security teams who need to evaluate the potential impact on their systems and take appropriate measures to mitigate the vulnerability.

Why it matters

This vulnerability can lead to a denial of service and potential data corruption or loss in Zephyr-based systems using the MCTP I2C+GPIO target binding. Defenders should prioritize verifying and applying patches for affected versions, as well as monitoring for potential exploitation attempts. The corpus does not establish versions beyond 4.4.2 or provide specific remediation steps beyond a patch commit, requiring further verification from official sources.

• Potential denial of service due to NULL pointer dereference
• Possible data corruption or loss due to improper handling of register and data-phase flags
• Need for verification of affected versions and application of patches
• Importance of monitoring for potential exploitation attempts

Technical summary

The MCTP-over-I2C+GPIO target binding in subsys/pmci/mctp/mctp_i2c_gpio_target.c emulates a small pseudo-register file, where the bus controller first writes a register number and then writes or reads payload bytes. The selected register (b->reg_addr) and the data-phase flag (b->rxtx) were never cleared when the controller issued an I2C STOP, so after a completed transfer the target still had a data register selected while the packet buffer that register refers to had already been consumed and set to NULL by mctp_i2c_gpio_target_stop().

Defensive priority

Defenders should prioritize verifying and applying patches for affected Zephyr versions, as well as monitoring for potential exploitation attempts.

Recommended defensive actions

• Verify and apply patches for affected Zephyr versions
• Monitor for potential exploitation attempts
• Review and update inventory of affected systems
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description, CVSS score, and affected versions. However, the corpus does not establish versions beyond 4.4.2 or provide specific remediation steps beyond a patch commit.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.