CVE-2026-19571 — Race condition in ITE IT8xxx2 SHI host-command backend lets a second SPI request write an unvalidated length into the in-flight request buffer
The ITE IT8xxx2 SHI host-command backend (subsys/mgmt/ec_host_cmd/backends/ec_host_cmd_backend_shi_ite.c) copied the 8-byte host-command request header from the SPI Rx FIFO directly into the shared receive buffer data->in_msg and only afterwards checked the protocol version and the derived packet length. The interrupt handler also accepted a chip-select assertion and an Rx-valid-length (RVLI) interrupt in any driver state other than SHI_STATE_DISABLED, so a new header could be parsed while the host-command thread was still processing the previous request out of the very same buffer. The host processor is the SPI controller and drives both chip select and the clock. After sending a well-formed request it can immediately de-assert chip select — which returns the driver to the ready state and re-enables the FIFO — and start a second transaction carrying a header with data_len = 0xFFFF. Those eight bytes are written into in_msg before the oversized length is rejected, so they land in a buffer whose contents verify_rx() in subsys/mgmt/ec_host_cmd/ec_host_cmd_handler.c has already validated. If this lands in the window before the host-command thread executes args.input_buf_size = rx_header->data_len, the framework hands the registered command handler a 65535-byte input length over a 256-byte buffer. The result is an out-of-bounds read of up to roughly 64 KiB beyond the request buffer: command handlers that copy or echo input_buf_size bytes disclose adjacent embedded-controller memory back to the host or overflow the response buffer, and a read past the end of SRAM faults the controller. The same race also allows cmd_id and cmd_ver to be swapped after checksum verification and after handler lookup. Exploitation requires the ability to drive the inter-processor SHI bus (a compromised host OS or physical access to the SPI lines) and winning a timing race, which the SPI controller can retry indefinitely. The fix parses the header into a local struct ec_host_cmd_request_header and copies it into in_msg only after the length has been bounded by sizeof(data->in_msg), and ignores chip-select and RVLI interrupts outside SHI_STATE_READY_TO_RECV/SHI_STATE_RECEIVING. A residual, bounded race remains: an end-of-transaction interrupt still resets the state to ready while the host-command thread owns the buffer, so a valid second request can still overwrite the in-flight request's contents, unlike the NPCX backend which parks in SHI_STATE_CNL_RESP_NOT_RDY while the buffer is in use.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.1% (30-day exploitation probability)+0
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Zephyrproject Zephyr).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (logic error), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Zephyrproject | Zephyr | ≥ 3.3.0 and < 4.5.0 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 6.7 | CVSS 3.1 | Medium | 1.4 | 5.2 | vulnerabilities@zephyrproject.org via NIST National Vulnerability Database |
| 6.7 | CVSS 3.1 | Medium | — | — | zephyr via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H (score shown at the top: vulnerabilities@zephyrproject.org) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.09%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · zephyrproject/zephyr
- SSVC assessment updated
- Record published
- CVSS changed · 6.7
- Source status changed · → Awaiting Analysis
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-75083 Integer underflow of the radio-reported frame length causes an out-of-bounds write in the NXP KW41Z IEEE 802.15.4 driver 1d
- Medium CVE-2026-75085 Out-of-bounds read from received-frame length underflow in the STM32WBA IEEE 802.15.4 driver 1d
- Medium CVE-2026-75084 Out-of-bounds write in the TI CC1200 IEEE 802.15.4 driver from an unvalidated radio-supplied packet length 1d
- High CVE-2026-19673 Out-of-bounds read and net_buf length underflow in Zephyr Ethernet L2 when parsing a truncated VLAN header 1d
- Medium CVE-2026-19940 Bluetooth HFP AG reuses a connection slot while a delayable work item is still armed, corrupting kernel timeout bookkeeping 2d
- Medium CVE-2026-19939 Bluetooth Classic AVDTP: stale timeout work on signalling-channel disconnect leads to kernel timeout-list corruption 2d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-19571 is "Race condition in ITE IT8xxx2 SHI host-command backend lets a second SPI request write an unvalidated length into the in-flight request buffer", rated Medium. It affects Zephyr (Zephyrproject); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.7 describes technical severity. EPSS 0.09% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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