In the Linux kernel, the following vulnerability has been resolved:
firewire: ohci: mask bus reset interrupts between ISR and bottom half
In the FireWire OHCI interrupt handler, if a bus reset interrupt has
occurred, mask bus reset interrupts until bus_reset_work has serviced and
cleared the interrupt.
Normally, we always leave bus reset interrupts masked. We infer the bus
reset from the self-ID interrupt that happens shortly thereafter. A
scenario where we unmask bus reset interrupts was introduced in 2008 in
a007bb857e0b26f5d8b73c2ff90782d9c0972620: If
OHCI_PARAM_DEBUG_BUSRESETS (8) is set in the debug parameter bitmask, we
will unmask bus reset interrupts so we can log them.
irq_handler logs the bus reset interrupt. However, we can't clear the bus
reset event flag in irq_handler, because we won't service the event until
later. irq_handler exits with the event flag still set. If the
corresponding interrupt is still unmasked, the first bus reset will
usually freeze the system due to irq_handler being called again each
time it exits. This freeze can be reproduced by loading firewire_ohci
with "modprobe firewire_ohci debug=-1" (to enable all debugging output).
Apparently there are also some cases where bus_reset_work will get called
soon enough to clear the event, and operation will continue normally.
This freeze was first reported a few months after a007bb85 was committed,
but until now it was never fixed. The debug level could safely be set
to -1 through sysfs after the module was loaded, but this would be
ineffectual in logging bus reset interrupts since they were only
unmasked during initialization.
irq_handler will now leave the event flag set but mask bus reset
interrupts, so irq_handler won't be called again and there will be no
freeze. If OHCI_PARAM_DEBUG_BUSRESETS is enabled, bus_reset_work will
unmask the interrupt after servicing the event, so future interrupts
will be caught as desired.
As a side effect to this change, OHCI_PARAM_DEBUG_BUSRESETS can now be
enabled through sysfs in addition to during initial module loading.
However, when enabled through sysfs, logging of bus reset interrupts will
be effective only starting with the second bus reset, after
bus_reset_work has executed.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (4.4): severity, escalated by confirmed exploitation. This CVE's 4.4 is its impact severity (EG Severity), not escalated.
- EG Severity
- 4.4 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 0.3% 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