CVE-2026-14605: Buffer Overflow in RT-Thread CAN Handler

Detection and Triage

Detection will be harder than for a web-facing CVE because this bug sits in a firmware code path, not a well-instrumented application stack. Many affected environments will have minimal logging, no EDR, and inconsistent crash reporting. Still, defenders can look for instability around CAN receive handling, recurring faults when malformed or boundary-value CAN frames are processed, and unexpected resets on devices using the ls1c CAN path.

At triage time, focus on evidence of three things: devices built with the vulnerable code, exposure of the CAN receive path, and anomalous behavior consistent with memory corruption. If your engineering teams can reproduce the issue in a test harness, that is often the fastest way to validate operational risk. If you cannot observe detailed logs from the production device, use adjacent telemetry such as watchdog resets, kernel panic output on serial consoles, or repeated service restarts after CAN traffic bursts.

Technical Notes

A practical source-based validation step is to search your firmware source tree and built artifacts for the vulnerable path and function name:

grep -R "bsp/loongson/ls1cdev/libraries/ls1c_can.h" .
grep -R "recvmsg" .
grep -R "rt_can_msg" .

If you have serial console logs or crash output from RT-Thread-based devices, look for patterns consistent with stack corruption or task crashes immediately after CAN activity. Exact log formats vary by build, so defenders should search broadly for fault indicators such as:

HardFault
stack overflow
assert failed
exception
task crash
watchdog reset
can rx
recvmsg

For environments collecting centralized logs from test benches or device gateways, a simple hunting query can help correlate resets with CAN events:

SELECT timestamp, device_id, message
FROM device_logs
WHERE message REGEXP '(can|CAN|recvmsg|rx)'
   OR message REGEXP '(HardFault|stack overflow|watchdog reset|assert|exception)'
ORDER BY timestamp DESC;

If you can inspect CAN traffic in a lab, watch for frames with suspicious or boundary-value DLC values repeatedly preceding device faults. Because the public evidence points to trust in a raw DLC field, malformed or inconsistent length-related input deserves scrutiny even if the exact exploit packet details are not available.

Mitigation and Patching

The most important mitigation fact is also the most frustrating one: no confirmed fixed version number is available from the retrieved primary references. The affected range is stated as RT-Thread through 5.0.2, but a specific “fixed in version X” statement could not be confirmed. That means you should not claim internal closure based solely on upgrading to an arbitrary newer release unless engineering has validated the relevant source change in your codebase.

If you use the affected BSP or CAN handler, the immediate mitigation path is to reduce exposure while pursuing an engineering fix. That can include disabling the ls1c CAN interface where it is not needed, limiting who or what can inject CAN traffic, isolating maintenance ports, and increasing monitoring around device resets and anomalous bus activity. For product makers, the stronger medium-term action is to review recvmsg and surrounding length handling, verify bounds checks against the destination buffer size, and backport any upstream fix once one is confirmed.

Technical Notes

If your environment tracks RT-Thread from the upstream repository, first identify the exact version in use:

git describe --tags
git rev-parse HEAD

If you are on 5.0.2 or earlier and the affected ls1c CAN code is present, assume exposure until disproven. A generic upgrade command may look like this in a source-based workflow:

git fetch --tags origin
git checkout v5.0.2

However, because the fixed version is unknown, do not interpret a checkout to a later tag as a confirmed remediation without verifying the code change. Instead, inspect the vulnerable function directly and apply a defensive workaround if necessary. For example, engineering teams should review the receive path for DLC bounds validation before any copy into rt_can_msg data. A conceptual mitigation is to clamp or reject invalid DLC values before writing:

if (msg->len > sizeof(can_msg.data)) {
    return -RT_ERROR;
}

That snippet is illustrative, not a vendor-issued patch. Your developers must confirm the correct variable names, data structures, and behavior for the actual RT-Thread ls1c CAN implementation. If you cannot patch immediately, consider disabling the affected feature in the build or preventing CAN input from untrusted sources until a verified fix is available.

References

• NVD CVE record: https://nvd.nist.gov/vuln/detail/CVE-2026-14605
• RT-Thread official site: https://www.rt-thread.io
• RT-Thread repository: https://github.com/RT-Thread/rt-thread/
• GitHub issue #11424: https://github.com/RT-Thread/rt-thread/issues/11424
• CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

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