Microchip ASF4 integer overflows in flash_read, flash_write and flash_append

CENSUS ID:	CENSUS-2020-0005
CVE ID:	CVE-2019-16127
Affected Products:	ASF4 as distributed through start.atmel.com (last accessed 2020-10-21)
Class:	Integer Overflow or Wraparound (CWE-190)
Discovered by:	George Poulios

CENSUS identified several integer overflow problems in the flash_read, flash_write and flash_append functions of the Microchip ASF4 framework. This framework is used during firmware development for Atmel (now Microchip) microcontrollers. An adversary may abuse these issues to gain unauthorized read or write access to arbitrary pages of the flash storage, especially pages mapped at low memory addresses. As no patch is available from the vendor, CENSUS urges developers to implement a check for integer overflows in the relevant code.