CVE-2026-10657
LowCVSS 3.7Exploitation Probability (EPSS)
Low risk15th percentile - higher than 15% of all known CVEs
Summary
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.
Risk Assessment
Operators or remote inputs (e.g., server names from configuration, parsed URLs) can trigger an out-of-bounds read. In tightly allocated buffers (e.g., from k_usermode_string_alloc_copy), this causes a critical fault and system disruption.
Recommendation
Immediately update Zephyr OS to a version containing the fix that replaces memcmp() with NUL-safe strcmp(). If updating is not possible, disable CONFIG_MDNS_RESOLVER in the kernel configuration.
Other vulnerabilities in Zephyr OS
See all- CVE-2026-17052High
The Time-aware GPIO driver in Zephyr OS lacks validation of output pointers in the tgpio_pin_read_ts_ec() syscall, allowing an unprivileged thread to write to arbitrary kernel memory. The vulnerability only affects builds with CONFIG_USERSPACE=y and CONFIG_TIMEAWARE_GPIO=y, and practical exposure is limited by build issues in some versions.
- CVE-2026-15893Medium
In Zephyr OS, the net_if_ipv6_calc_reachable_time() function in subsys/net/ip/net_if.c incorrectly calculates the neighbor reachable time when base_reachable_time is 1, resulting in a value of 0. An attacker can send an unauthenticated Router Advertisement with the Reachable Time field set to 1, causing the reachable time to be zeroed. Consequently, when a neighbor is confirmed reachable, a kernel assertion may occur (if CONFIG_ASSERT is enabled) or the timer fires immediately, leading to constant re-solicitation and degradation of Neighbor Discovery.
- CVE-2026-13216Medium
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.
- 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-2026-10656Medium
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.
Original NVD description (English source)
Zephyr's DNS resolver detects mDNS (.local) queries in dns_resolve_name_internal() (subsys/net/lib/dns/resolve.c) with memcmp(strrchr(query, '.'), ".local", 7), which always reads a fixed 7 bytes from the suffix pointer. When the resolved hostname's final label is shorter than 7 bytes (e.g. names ending in .org, .com, .net, .io, or a trailing dot), the comparison reads 1-2 bytes past the string's NUL terminator. The hostname (query) is the caller-supplied name passed through the standard getaddrinfo()/dns_get_addr_info()/dns_resolve_name() path and is influenceable by operators or remote inputs (server names from configuration, parsed URLs, or app-facing interfaces). On a tightly-sized buffer with no slack (for example a userspace getaddrinfo call where the hostname is copied with k_usermode_string_alloc_copy to exactly strlen+1 bytes), the over-read crosses the allocation boundary; if that boundary is unmapped (guard page, memory-domain boundary under MPU, or an address sanitizer) the over-read faults, causing a denial of service. The over-read bytes are never returned, so there is no information disclosure. The flaw is compiled only when CONFIG_MDNS_RESOLVER is enabled, exists since v1.10.0, and is fixed by replacing the fixed-length memcmp with a NUL-safe strcmp(ptr, ".local").
Vulnerability data from NVD (NIST) · CISA KEV · EPSS