Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
CVE-2026-64417
Linux Linux — mm: shrinker: fix NULL pointer dereference in debugfs
AV AC PR UI S C I A CVSS EPSS %ile KEV
L L L N U N N H 5.5 .0016 4.9 —
AFFECTED
Product Versions Fixed
Linux bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 – —
Linux 6.0 – 6.1.178
TIMELINE
Jul 19 Reserved by Linux
Jul 25 Published (CNA: Linux)
Sep 4 ENRICHED — CVE-2026-64417 (Linux). Received CVSS 5.5 and CPE data from NVD.
Description
In the Linux kernel, the following vulnerability has been resolved:
mm: shrinker: fix NULL pointer dereference in debugfs
shrinker_debugfs_add() creates both "count" and "scan" debugfs files
unconditionally.
That assumes every shrinker implements both count_objects() and
scan_objects(), which is not guaranteed. For example, the xen-backend
shrinker sets count_objects() but leaves scan_objects() NULL, so writing
to its scan file calls through a NULL function pointer and panics the
kernel:
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
Call Trace:
<TASK>
shrinker_debugfs_scan_write+0x12e/0x270
full_proxy_write+0x5f/0x90
vfs_write+0xde/0x420
? filp_flush+0x75/0x90
? filp_close+0x1d/0x30
? do_dup2+0xb8/0x120
ksys_write+0x68/0xf0
? filp_flush+0x75/0x90
do_syscall_64+0xb3/0x5b0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
The count path has the same issue in principle if a shrinker omits
count_objects().
To fix it, only create "count" and "scan" debugfs files when the
corresponding callbacks are present.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
| July 19, 2026 | Reserved | Reserved by Linux |
| July 25, 2026 | Published | Published (CNA: Linux) |
| September 4, 2026 | ENRICHED | ENRICHED — CVE-2026-64417 (Linux). Received CVSS 5.5 and CPE data from NVD. |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
| Linux | Linux | — | bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 | — |
| Linux | Linux | — | 6.0 | 6.1.178 |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-64417 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.