In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: Fix qi_batch NULL pointer with nested parent domain
The qi_batch is allocated when assigning cache tag for a domain. While
for nested parent domain, it is missed. Hence, when trying to map pages
to the nested parent, NULL dereference occurred. Also, there is potential
memleak since there is no lock around domain->qi_batch allocation.
To solve it, add a helper for qi_batch allocation, and call it in both
the __cache_tag_assign_domain() and __cache_tag_assign_parent_domain().
BUG: kernel NULL pointer dereference, address: 0000000000000200
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 8104795067 P4D 0
Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 223 UID: 0 PID: 4357 Comm: qemu-system-x86 Not tainted 6.13.0-rc1-00028-g4b50c3c3b998-dirty #2632
Call Trace:
? __die+0x24/0x70
? page_fault_oops+0x80/0x150
? do_user_addr_fault+0x63/0x7b0
? exc_page_fault+0x7c/0x220
? asm_exc_page_fault+0x26/0x30
? cache_tag_flush_range_np+0x13c/0x260
intel_iommu_iotlb_sync_map+0x1a/0x30
iommu_map+0x61/0xf0
batch_to_domain+0x188/0x250
iopt_area_fill_domains+0x125/0x320
? rcu_is_watching+0x11/0x50
iopt_map_pages+0x63/0x100
iopt_map_common.isra.0+0xa7/0x190
iopt_map_user_pages+0x6a/0x80
iommufd_ioas_map+0xcd/0x1d0
iommufd_fops_ioctl+0x118/0x1c0
__x64_sys_ioctl+0x93/0xc0
do_syscall_64+0x71/0x140
entry_SYSCALL_64_after_hwframe+0x76/0x7e
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