In the Linux kernel, the following vulnerability has been resolved:
iommufd: Set end correctly when doing batch carry
Even though the test suite covers this it somehow became obscured that
this wasn't working.
The test iommufd_ioas.mock_domain.access_domain_destory would blow up
rarely.
end should be set to 1 because this just pushed an item, the carry, to the
pfns list.
Sometimes the test would blow up with:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] SMP
CPU: 5 PID: 584 Comm: iommufd Not tainted 6.5.0-rc1-dirty #1236
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:batch_unpin+0xa2/0x100 [iommufd]
Code: 17 48 81 fe ff ff 07 00 77 70 48 8b 15 b7 be 97 e2 48 85 d2 74 14 48 8b 14 fa 48 85 d2 74 0b 40 0f b6 f6 48 c1 e6 04 48 01 f2 <48> 8b 3a 48 c1 e0 06 89 ca 48 89 de 48 83 e7 f0 48 01 c7 e8 96 dc
RSP: 0018:ffffc90001677a58 EFLAGS: 00010246
RAX: 00007f7e2646f000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 00000000fefc4c8d RDI: 0000000000fefc4c
RBP: ffffc90001677a80 R08: 0000000000000048 R09: 0000000000000200
R10: 0000000000030b98 R11: ffffffff81f3bb40 R12: 0000000000000001
R13: ffff888101f75800 R14: ffffc90001677ad0 R15: 00000000000001fe
FS: 00007f9323679740(0000) GS:ffff8881ba540000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000105ede003 CR4: 00000000003706a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
? show_regs+0x5c/0x70
? __die+0x1f/0x60
? page_fault_oops+0x15d/0x440
? lock_release+0xbc/0x240
? exc_page_fault+0x4a4/0x970
? asm_exc_page_fault+0x27/0x30
? batch_unpin+0xa2/0x100 [iommufd]
? batch_unpin+0xba/0x100 [iommufd]
__iopt_area_unfill_domain+0x198/0x430 [iommufd]
? __mutex_lock+0x8c/0xb80
? __mutex_lock+0x6aa/0xb80
? xa_erase+0x28/0x30
? iopt_table_remove_domain+0x162/0x320 [iommufd]
? lock_release+0xbc/0x240
iopt_area_unfill_domain+0xd/0x10 [iommufd]
iopt_table_remove_domain+0x195/0x320 [iommufd]
iommufd_hw_pagetable_destroy+0xb3/0x110 [iommufd]
iommufd_object_destroy_user+0x8e/0xf0 [iommufd]
iommufd_device_detach+0xc5/0x140 [iommufd]
iommufd_selftest_destroy+0x1f/0x70 [iommufd]
iommufd_object_destroy_user+0x8e/0xf0 [iommufd]
iommufd_destroy+0x3a/0x50 [iommufd]
iommufd_fops_ioctl+0xfb/0x170 [iommufd]
__x64_sys_ioctl+0x40d/0x9a0
do_syscall_64+0x3c/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.8): severity, escalated by confirmed exploitation. This CVE's 8.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.8 HIGHCVSS-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 2026-10-27). 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