CVE-2026-108952: RT-Thread through 5.3.0 Memory Corruption via USB CDC VCOM Driver

Severity: medium (CVSS 4.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-12 · updated 2026-10-16
Weakness: CWE-843

Description

RT-Thread through 5.3.0 contains a memory corruption vulnerability in the legacy USB CDC virtual COM port driver that aliases rx_ringbuffer as a Serial V2 rt_serial_rx_fifo in _function_enable(). A connected USB host configuring the CDC device triggers writes past the ring buffer into struct vcom members and an invalid rt_free() on close, causing denial of service.

Affected products

RT-Thread: through 5.3.0

References

https://github.com/RT-Thread/rt-thread
https://github.com/RT-Thread/rt-thread/blob/99428a1e7f7447955aa860f7c969273a12095b8f/components/legacy/usb/usbdevice/class/cdc_vcom.c#L518
https://github.com/RT-Thread/rt-thread/commit/ceef6e0ccd646aef61b907aeb9f29269d1caba50
https://github.com/RT-Thread/rt-thread/issues/11739
https://github.com/RT-Thread/rt-thread/pull/11770
https://www.vulncheck.com/advisories/rt-thread-through-5.3.0-memory-corruption-via-usb-cdc-vcom-driver

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