zephyrproject zephyr up to 4.4.x uart_mchp_sercom_g1.c uart_rx_enable out-of-bounds write

Summaryinfo

A vulnerability classified as critical was found in zephyrproject zephyr up to 4.4.x. Impacted is the function uart_rx_enable of the file drivers/serial/uart_mchp_sercom_g1.c. Executing a manipulation can lead to out-of-bounds write. This vulnerability is registered as CVE-2026-10644. The attack requires access to the local network. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical was found in zephyrproject zephyr up to 4.4.x. This vulnerability affects the function uart_rx_enable of the file drivers/serial/uart_mchp_sercom_g1.c. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

The Microchip SERCOM-G1 UART driver (drivers/serial/uart_mchp_sercom_g1.c), used by the PIC32CM-JH SoC family, contains an out-of-bounds write in its asynchronous (DMA) receive path. When uart_rx_enable() is invoked with a one-byte receive buffer (len == 1) and CONFIG_UART_MCHP_ASYNC is enabled, the RX-complete ISR starts a single-beat DMA transfer while a received byte is already pending in the SERCOM DATA register. On this SoC the peripheral-triggered DMA start sequencing then writes one byte past the end of the caller-supplied buffer (CWE-787). The overflowed byte's value is the UART RX data supplied by the connected serial peer (adjacent attacker), while its size and location are fixed at one byte immediately after the buffer. Exploitation requires the async UART config (not enabled by default on the in-tree PIC32CM-JH boards) and a consumer that enables RX with a one-byte buffer; impact is limited single-byte memory corruption adjacent to the RX buffer (possible crash / denial of service). The defect shipped in v4.4.0. The fix reads the first byte with the CPU and, for one-byte buffers, performs no DMA at all; for larger buffers it sizes the DMA for the remaining len-1 bytes.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-10644 since 06/02/2026. The exploitation appears to be difficult. The attack needs to approached within the local network. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available.

Upgrading to version 4.5.0 eliminates this vulnerability. Applying the patch 5251d2bc0070be801769fb7ce7b9066fef5d9f81 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-39979). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Project Management Software

Vendor

• zephyrproject

Name

• zephyr

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4

License

• open-source

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Once again VulDB remains the best source for vulnerability data.

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