CVE-2026-15893
MediumCVSS 6.5Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
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.
Risk Assessment
The vulnerability allows a remote denial-of-service attack on Zephyr OS systems reachable on the local network. The attack requires no authentication and can cause system crashes or significant network performance degradation.
Recommendation
It is recommended to update Zephyr OS to a patched version and, if possible, enable authentication for Router Advertisements (e.g., SEND) or filter unauthenticated RAs.
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-2026-13216Medium
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-2026-10657Low
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.
Original NVD description (English source)
net_if_ipv6_calc_reachable_time() in subsys/net/ip/net_if.c derives a randomized ND reachable time from ipv6->base_reachable_time as min_reachable + sys_rand32_get() % (max_reachable - min_reachable), where min_reachable = base/2 and max_reachable = 3*base/2 using integer division. When base_reachable_time is 1, both min_reachable and the modulus collapse so the function returns 0, and net_if_ipv6_set_reachable_time() stores that 0 into ipv6->reachable_time. The base_reachable_time is attacker-controlled: handle_ra_input() in subsys/net/ip/ipv6_nbr.c accepts the Reachable Time field of an incoming Router Advertisement whenever it is nonzero and <= MAX_REACHABLE_TIME, so a single unauthenticated, link-local RA carrying a Reachable Time of 1 drives the computed reachable time to 0. Router Advertisements are unauthenticated by default and require only adjacency to the target link. When a neighbor is subsequently confirmed reachable, net_ipv6_nbr_set_reachable_timer() reads the value and executes NET_ASSERT(time, "Zero reachable timeout!"). On builds with CONFIG_ASSERT enabled this triggers a fatal kernel assertion — a remote denial of service; on builds without assertions the reachable timer is armed with K_MSEC(0) and fires immediately, forcing reachable neighbors into perpetual re-solicitation (STALE), degrading Neighbor Discovery. The impact is limited to availability; there is no memory-safety, confidentiality, or integrity consequence.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

