Out-of-bounds write in Microchip SERCOM-G1 (PIC32CM-JH) async UART RX with 1-byte buffer

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Summary

CVECVE-2026-10644
StatePUBLISHED
Assignerzephyr
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-28 05:16:20 UTC
Updated2026-07-06 19:43:47 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 3.1 LOW from [email protected]

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS: 0.001480000 probability, percentile 0.044300000 (date 2026-07-08)

Problem Types: CWE-787 | CWE-787 bounds

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary3.1LOWCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1[email protected]Secondary4.2MEDIUMCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
3.1CNACVSS4.2MEDIUMCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Zephyrproject Zephyr All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Zephyrproject Zephyr affected 4.4.0 4.5.0 semver Not specified

References

ReferenceSourceLinkTags
github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-xv2x-56j7-... [email protected] github.com Exploit, Patch, Vendor Advisory
github.com/zephyrproject-rtos/zephyr/commit/5251d2bc0070be801769fb7ce7b9... [email protected] github.com Patch
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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