In the Linux kernel, the following vulnerability has been resolved:
serial: sc16is7xx: fix invalid FIFO access with special register set
When enabling access to the special register set, Receiver time-out and
RHR interrupts can happen. In this case, the IRQ handler will try to read
from the FIFO thru the RHR register at address 0x00, but address 0x00 is
mapped to DLL register, resulting in erroneous FIFO reading.
Call graph example:
sc16is7xx_startup(): entry
sc16is7xx_ms_proc(): entry
sc16is7xx_set_termios(): entry
sc16is7xx_set_baud(): DLH/DLL = $009C --> access special register set
sc16is7xx_port_irq() entry --> IIR is 0x0C
sc16is7xx_handle_rx() entry
sc16is7xx_fifo_read(): --> unable to access FIFO (RHR) because it is
mapped to DLL (LCR=LCR_CONF_MODE_A)
sc16is7xx_set_baud(): exit --> Restore access to general register set
Fix the problem by claiming the efr_lock mutex when accessing the Special
register set.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it