CVE-2026-87042zephyrproject zephyr uncontrolled resource consumption
CVE-2026-87042 is a uncontrolled resource consumption in zephyrproject zephyr, rated medium (6.5 on CVSS 3.1).
Why this priority: Medium severity, with no exploitation signal.
Published · Updated · NVD status: Awaiting Analysis
What it is
Requests can consume unbounded CPU, memory or connections and starve the service.
How it is reached
An attacker can exploit it from the same local network segment, without an account, and nobody has to click anything.
What an attacker gains
A successful attack can take it offline. In practice, this kind of flaw lets an attacker exhaust CPU, memory or connections until the service stops answering.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Upgrade zephyrproject zephyr to a fixed version for your release line (4.3.2, 4.5.0).
- Segment the networks that can reach it.
Description from NVD
The IEEE 1588 (PTP) port implementation in subsys/net/lib/ptp/port.c adopted the logMessageInterval field of a received Delay_Resp message without any validation. port_delay_resp_msg_process() stored the raw wire value (a full-range int8_t) into port_ds.log_min_delay_req_interval, and that value is later used as a shift count by port_timer_set_timeout() when the Delay_Req timer is armed. Values below about -30 truncate the computed timeout to zero, and values with a magnitude of 64 or more perform an undefined shift of a uint64_t; the standards-defined "not applicable" encoding 0x7F fell into the latter case as well.
PTP messages are received over unauthenticated link-local traffic (UDP multicast on 224.0.1.129, IPv6 multicast, or raw IEEE 802.3), and the handler accepts a Delay_Resp from any sender as long as the port is a time receiver using the end-to-end delay mechanism and the message echoes the port identity and a pending sequence id — both of which the victim itself broadcasts in its Delay_Req. Any node on the same link can therefore inject a single crafted Delay_Resp, or simply become the time transmitter and advertise the bogus interval.
Once the delay timer is armed with a zero timeout, the cooperative PTP thread re-arms and retransmits a Delay_Req on every tick. Each transmission takes a buffer from the fixed CONFIG_PTP_MSG_POLL_SIZE message slab (default 10) and holds it on port->delay_req_list for three seconds, so the slab is emptied within milliseconds and ptp_msg_alloc() then blocks with K_FOREVER inside the only thread that frees those buffers — permanently stalling time synchronization until reboot. Where a transmit-timestamp callback on another thread keeps recycling buffers, the result is instead a sustained multicast Delay_Req flood and continuous CPU consumption. There is no memory corruption and no disclosure of data; the impact is availability of the PTP subsystem and of the local network segment.
The fix rejects intervals outside a representable range and treats 0x7F as "not applicable" as required by IEEE 1588-2019 Table 42. The equivalent unchecked adoption of logMessageInterval from Sync messages in port_sync_msg_process(), a weaker variant of the same issue, is fixed by the companion change 334bf57f416f (#118150), which applies the same range check, ignores the field for unicast Sync messages and treats 0x7F as not applicable.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Public entry points and shared services that must stay up. The flaw sits between untrusted traffic and shared capacity.
Trust boundaries in play
- Local network segment. The attacker must share a network segment with the target.
- Between untrusted traffic and shared capacity. An attacker who crosses it can exhaust CPU, memory or connections until the service stops answering.
Questions to answer about your own systems
- Where does zephyrproject zephyr run in your systems, and at which version?
- Which network segments can reach them?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.