In the Linux kernel, the following vulnerability has been resolved:
iommufd: Require drivers to supply the cache_invalidate_user ops
If drivers don't do this then iommufd will oops invalidation ioctls with
something like:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
ESR = 0x0000000086000004
EC = 0x21: IABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000101059000
[0000000000000000] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000086000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 2 PID: 371 Comm: qemu-system-aar Not tainted 6.8.0-rc7-gde77230ac23a #9
Hardware name: linux,dummy-virt (DT)
pstate: 81400809 (Nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=-c)
pc : 0x0
lr : iommufd_hwpt_invalidate+0xa4/0x204
sp : ffff800080f3bcc0
x29: ffff800080f3bcf0 x28: ffff0000c369b300 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
x23: 0000000000000000 x22: 00000000c1e334a0 x21: ffff0000c1e334a0
x20: ffff800080f3bd38 x19: ffff800080f3bd58 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 0000ffff8240d6d8
x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000001000000002 x7 : 0000fffeac1ec950 x6 : 0000000000000000
x5 : ffff800080f3bd78 x4 : 0000000000000003 x3 : 0000000000000002
x2 : 0000000000000000 x1 : ffff800080f3bcc8 x0 : ffff0000c6034d80
Call trace:
0x0
iommufd_fops_ioctl+0x154/0x274
__arm64_sys_ioctl+0xac/0xf0
invoke_syscall+0x48/0x110
el0_svc_common.constprop.0+0x40/0xe0
do_el0_svc+0x1c/0x28
el0_svc+0x34/0xb4
el0t_64_sync_handler+0x120/0x12c
el0t_64_sync+0x190/0x194
All existing drivers implement this op for nesting, this is mostly a
bisection aid.
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