CVE-2026-90590zephyrproject zephyr resource never released
CVE-2026-90590 is a resource never released 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
Resources are not released after use, so repeated requests exhaust them.
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 NXP ENET QoS Ethernet driver in drivers/ethernet/eth_nxp_enet_qos serialises transmission with a binary semaphore, data->tx.tx_sem, taken in eth_nxp_enet_qos_tx() and returned only by the transmit-completion interrupt handler tx_dma_done(). A frame that has been handed to the transmit DMA when the Ethernet link goes down is never written back, so that completion interrupt never arrives. The PHY callback eth_nxp_enet_qos_phy_cb() reacts to carrier loss only by calling net_eth_carrier_set(); it does not stop the DMA, take the descriptors back or release the outstanding frame, and no timeout exists to do so.
The trigger is a link-down/link-up transition that lands while a frame is under the transmit DMA. It can be produced by anyone who controls the link partner or the cable — for example by administratively downing and restoring the attached switch port, or by restarting auto-negotiation from a peer device — and can be made reliable by generating traffic that keeps the device transmitting and repeating the transition. No credentials or user interaction are required, and the trigger is at the link layer rather than over IP.
Because the semaphore is never given back, every subsequent call to eth_nxp_enet_qos_tx() fails with -EBUSY for the remaining life of the boot; restoring the link does not recover the interface, since the link-up path only rewrites MAC_CONFIGURATION. The affected interface continues to receive but can no longer transmit anything — no ARP replies, no TCP acknowledgements, no DHCP renewals — until the device is reset. The net_pkt and the net_buf fragments of the abandoned frame are likewise never unreferenced and never return to their pools. The security-relevant property is persistence: a momentary link flap leaves the interface permanently unable to send, so the denial of service outlasts the attacker's access to the link. There is no confidentiality or integrity impact.
The fix adds a claim/release pair around the outstanding packet so that completion and abandonment are mutually exclusive, aborts an outstanding frame from the PHY callback on carrier loss (stopping the DMA, flushing the MTL transmit queue and reinitialising the descriptor ring), and arms a transmit watchdog, CONFIG_ETH_NXP_ENET_QOS_TX_TIMEOUT_MS, so that any non-completing DMA — not only a carrier loss — reclaims the transmit slot and the packet.
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.