CVE-2026-13216
MediumCVSS 6.1Exploitation Probability (EPSS)
Low risk8th percentile - higher than 8% of all known CVEs
Summary
The virtio PCI driver in Zephyr OS (drivers/virtio/virtio_pci.c) improperly validates the capability length (cap_len) read from PCI configuration space. The lack of runtime validation (assert is disabled in production builds) leads to an out-of-bounds write on the kernel stack during device initialization.
Risk Assessment
A malicious virtio PCIe device (e.g., physical or passed through to a guest) can overwrite the kernel stack, potentially causing a system crash or arbitrary code execution in kernel mode. In typical hypervisor deployments the risk is limited, but on bare-metal systems or in confidential computing scenarios it poses a serious threat.
Recommendation
Update Zephyr OS immediately to a version containing the fix that adds a runtime range check for cap_len before it is used in copy operations. Until updated, avoid using untrusted virtio PCIe devices.
Other vulnerabilities in Zephyr OS
See all- CVE-2026-11809Low
The UpdateHub OTA client in Zephyr OS contains an uninitialized heap memory read and out-of-bounds read in z_impl_updatehub_probe(). A malicious UpdateHub server can send a crafted response that, after a failed first JSON parse, uses a non-NUL-terminated metadata_copy buffer, leading to a read past the allocated memory and potentially crashing the device.
- CVE-2026-11368High
A vulnerability in the ATT layer of the Bluetooth stack in Zephyr OS leads to a use-after-free of channel memory. When a remote device disconnects during ongoing ATT traffic, a deferred callback may reference a freed channel, causing a system crash or potential memory corruption.
- CVE-2026-10677Medium
In Zephyr OS (versions v1.12.0 through v4.4.1), the CONFIG_USERSPACE syscall verifier in z_vrfy_k_poll() does not free memory on validation failure. An attacker can repeatedly trigger a memory leak, exhausting the kernel pool and causing denial of service.
- CVE-2026-10674Medium
In Zephyr OS (since v2.5.0), the NXP LPUART driver disables peripheral clocks before validating configuration. Unsupported parameters cause an error without re-enabling the clock, leading to a hard fault and system crash.
- CVE-2026-10666High
A stack buffer overflow vulnerability exists in the parse_ipv4() function in Zephyr OS. An attacker can craft an IP address with a long suffix after the colon, causing data to be copied beyond the allocated 17-byte buffer. The issue has been present since v1.9.0 through v4.4.0 and can lead to system crashes or potential control-flow hijack.
- CVE-2026-10657Low
In Zephyr OS, a vulnerability in the DNS resolver uses memcmp() to always compare 7 bytes with the ".local" suffix, even when the final hostname label is shorter. This causes an out-of-bounds read past the string terminator, potentially leading to a page fault and denial of service (DoS). The flaw is present only when CONFIG_MDNS_RESOLVER is enabled and exists since v1.10.0.
- CVE-2026-10656Medium
The MAX32xxx USB device controller driver (udc_max32.c) in Zephyr OS does not check if the endpoint buffer is NULL in the OUT and IN transfer-completion handlers. When a USB host sends a new SETUP packet during an ongoing EP0 transfer, the FIFO can be drained, causing a stale event to be processed, leading to a near-NULL pointer dereference and device crash.
- CVE-2026-10648Medium
In Zephyr OS, the mcumgr_serial_process_frag() function calls net_buf_reset() on the result of smp_packet_alloc() before checking for NULL. When the MCUmgr packet pool (default 4 buffers) is exhausted, smp_packet_alloc() returns NULL, and writing through the NULL pointer causes a system crash.
- CVE-2026-10642Medium
The Zephyr PL011 UART driver (drivers/serial/uart_pl011.c) has an unbounded loop in pl011_irq_tx_enable() that hangs the thread when CTS hardware flow control is enabled and the peer de-asserts CTS. The loop never exits because the TX FIFO cannot drain, causing a denial of service (CWE-835).
Original NVD description (English source)
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. The 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. The 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. The 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.