In the Linux kernel, the following vulnerability has been resolved:
HID: appletb-kbd: run inactivity autodim from workqueues
The autodim code in hid-appletb-kbd takes backlight_device->ops_lock
via backlight_device_set_brightness() -> mutex_lock() from two
different atomic contexts:
* appletb_inactivity_timer() is a struct timer_list callback, so it
runs in softirq context. Every expiry triggers
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:591
Call Trace:
__might_resched
__mutex_lock
backlight_device_set_brightness
appletb_inactivity_timer
call_timer_fn
run_timer_softirq
* reset_inactivity_timer() is called from appletb_kbd_hid_event() and
appletb_kbd_inp_event(). On real USB hardware these run in
softirq/IRQ context (URB completion and input-event dispatch).
When the Touch Bar has already been dimmed or turned off, the
reset path calls backlight_device_set_brightness() directly to
restore brightness, producing the same warning.
Both call sites hit the same mutex_lock()-from-atomic bug. Fix them
together by moving the blocking work onto the system workqueue:
* Convert the inactivity timer from struct timer_list to
struct delayed_work; the callback (appletb_inactivity_work) now
runs in process context where mutex_lock() is legal.
* Add a dedicated struct work_struct restore_brightness_work and have
reset_inactivity_timer() schedule it instead of calling
backlight_device_set_brightness() directly.
Cancel both works synchronously during driver tear-down alongside the
existing backlight reference drop.
The semantics are unchanged (same delays, same state transitions on
dim, turn-off and user activity); only the execution context of the
sleeping call changes. The timer field and callback are renamed to
match their new type; reset_inactivity_timer() keeps its name because
it is invoked from input event paths that read naturally as "reset
the inactivity timer".
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
- 0.1% within 30 daysSource: FIRST EPSS. 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 low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 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 low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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)14 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's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” 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