CVE-2026-10644

What it is

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.

At a glance

Exploitability

Can be exploited from the same network segment without logging in. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-06-28 05:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-25 17:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 4.2 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-06-28 05:16 UTC

Last modified

2026-10-25 17:10 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-787 · Out-of-bounds write

Record status

Modified

Affected

• Zephyrproject Zephyr ≤ 4.4.1

Attack profile CVSS 3.1 · 4.2

Attack vector

Adjacent network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

Low

Is it in your code?

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