{"affected":[{"defaultStatus":"unaffected","ecosystem":"https://github.com/zephyrproject-rtos/zephyr","packageName":"zephyr","product":"zephyr","source":"CNA: zephyr","vendor":"zephyrproject","versions":[{"lessThan":"4.3.2","status":"affected","version":"4.2.0","versionType":"semver"},{"lessThan":"4.4.2","status":"affected","version":"4.4.0","versionType":"semver"}]}],"cveId":"CVE-2026-13216","cwes":["CWE-787"],"description":"The virtio PCI driver (drivers/virtio/virtio_pci.c) parses a device's PCI capability list during driver initialization. In virtio_pci_read_cap() the device-supplied capability length byte cap_len (read from PCI config space via pcie_conf_read()) was only checked with assert(tmp.cap_len == cap_struct_size). That assert resolves to __ASSERT_NO_MSG(), gated by CONFIG_ASSERT, which defaults off in production builds, so the value reached the copy logic completely unvalidated.\n\nThe length then drives a loop that copies extra capability dwords into a fixed-size stack buffer supplied by the caller. A cap_len below the 24-byte base struct virtio_pci_cap underflows the unsigned extra_data_words count to a near-SIZE_MAX value, producing an effectively unbounded stack write; a cap_len above the caller's buffer (up to 255) writes up to roughly 228 bytes of device-controlled data past the buffer. Both are out-of-bounds writes of attacker-controlled content executed in kernel mode during boot-time device probe.\n\nThe input originates from the virtio device. In the common deployment where Zephyr runs as a guest under a hypervisor, the device backend is the host, which already fully outranks the guest, so the bug yields no privilege escalation. The exploitable case is a virtio device that is untrusted relative to the Zephyr kernel — an untrusted or physical/passthrough virtio PCIe device on a bare-metal system, or a confidential-computing posture where the guest must defend against the host — where a malicious device can corrupt the kernel stack and potentially achieve code execution or a crash.\n\nThe fix replaces the compiled-out assert with a runtime range check rejecting cap_len outside [sizeof(struct virtio_pci_cap), cap_struct_size] before any arithmetic or copy.","epss":{"date":"2026-11-03","percentile":0.17381,"score":0.00257},"exploits":[],"kev":null,"metrics":[{"score":6.1,"severity":"medium","source":"CNA: zephyr","vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","version":"3.1"},{"score":6.1,"severity":"medium","source":"NVD: vulnerabilities@zephyrproject.org","vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","version":"3.1"}],"modifiedAt":1793769521863,"publishedAt":1787673936964,"references":[{"source":"CNA: zephyr","tags":["patch"],"url":"https://github.com/zephyrproject-rtos/zephyr/commit/d98dacee24ad10c972d3b7281c9009d82ed351c9"},{"source":"CNA: zephyr","tags":[],"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-qrh3-4mvv-w667"},{"source":"vulnerabilities@zephyrproject.org","tags":[],"url":"https://github.com/zephyrproject-rtos/zephyr/commit/d98dacee24ad10c972d3b7281c9009d82ed351c9"},{"source":"vulnerabilities@zephyrproject.org","tags":[],"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-qrh3-4mvv-w667"}],"remediation":[{"kind":"fix","source":"CNA: zephyr","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/zephyrproject-rtos/zephyr/commit/d98dacee24ad10c972d3b7281c9009d82ed351c9"}],"revision":"b3c0e455a4420cffa08a1f77706f01711dbec8521a4d4a34ef5c16b1e3b7d72d","sources":[{"modifiedAt":1793768393637,"name":"CNA: zephyr","retrievedAt":1793769035910,"url":"https://www.cve.org/CVERecord?id=CVE-2026-13216"},{"modifiedAt":1793769521863,"name":"NVD","retrievedAt":1793772961829,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-13216"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1793769047605,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-13216"}],"ssvc":{"assessedAt":1787686884460,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"total"},"status":"published","title":"Out-of-bounds stack write in Zephyr virtio PCI driver from unvalidated device-supplied capability length","updatedAt":1793772961829}