In the Linux kernel, the following vulnerability has been resolved:
serial: core: Clearing the circular buffer before NULLifying it
The circular buffer is NULLified in uart_tty_port_shutdown()
under the spin lock. However, the PM or other timer based callbacks
may still trigger after this event without knowning that buffer pointer
is not valid. Since the serial code is a bit inconsistent in checking
the buffer state (some rely on the head-tail positions, some on the
buffer pointer), it's better to have both aligned, i.e. buffer pointer
to be NULL and head-tail possitions to be the same, meaning it's empty.
This will prevent asynchronous calls to dereference NULL pointer as
reported recently in 8250 case:
BUG: kernel NULL pointer dereference, address: 00000cf5
Workqueue: pm pm_runtime_work
EIP: serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809)
...
? serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809)
__start_tx (drivers/tty/serial/8250/8250_port.c:1551)
serial8250_start_tx (drivers/tty/serial/8250/8250_port.c:1654)
serial_port_runtime_suspend (include/linux/serial_core.h:667 drivers/tty/serial/serial_port.c:63)
__rpm_callback (drivers/base/power/runtime.c:393)
? serial_port_remove (drivers/tty/serial/serial_port.c:50)
rpm_suspend (drivers/base/power/runtime.c:447)
The proposed change will prevent ->start_tx() to be called during
suspend on shut down port.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-25). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
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.
The score's inputs: 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