SMM Arbitrary Memory Access via Flash Handler with Unchecked FuncBlock Pointer
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.8epss 0.2%
exploitation probability
0.2%top 91% of all CVEs
observed exploitation
nono source reports it
A vulnerability in the Software SMI handler (SwSmiInputValue 0x20) allows a local attacker to supply a crafted pointer (FuncBlock) through RBX and RCX register values. This pointer is passed unchecked into multiple flash management functions (ReadFlash, WriteFlash, EraseFlash, and GetFlashInfo) that dereference both the structure and its nested members, such as BufAddr. This enables arbitrary read/write access to System Management RAM (SMRAM), allowing an attacker to corrupt firmware memory, exfiltrate SMRAM content via flash, or install persistent implants.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected products
GIGABYTE · UEFI-SmiFlash