CVE-2026-13212

Code execution via unchecked virtio descriptor index

Published Aug 24, 2026 · Updated Aug 24, 2026

Improper array-index validation in Zephyr RTOS 4.2.0 through 4.4.1 allows attackers to execute code via a malicious virtio backend. virtio_isr() uses the device-written used-ring descriptor ID to index recv_cbs[] and desc[] without checking it against vq->num, then invokes the out-of-bounds callback pointer. The path requires CONFIG_VIRTIO with PCI or MMIO transport; a compromised hypervisor or peer device can hijack guest control flow or crash the guest without guest privileges or user interaction.

CVSS severity8.8
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper array-index validation in Zephyr RTOS 4.2.0 through 4.4.1 allows attackers to execute code via a malicious virtio backend. virtio_isr() uses the device-written used-ring descriptor ID to index recv_cbs[] and desc[] without checking it against vq->num, then invokes the out-of-bounds callback pointer. The path requires CONFIG_VIRTIO with PCI or MMIO transport; a compromised hypervisor or peer device can hijack guest control flow or crash the guest without guest privileges or user interaction.

The record

CVE
CVE-2026-13212
Published
Aug 24, 2026
Updated
Aug 24, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-129
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.2.0 <4.4.2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=4.2.0 <4.4.2

Published CVSS scores

8.8GitHub Security AdvisoryCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-129Improper Validation of Array Index

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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