VulnerabilityPublished 18 Jun 2025Updated 5 Nov 2026

CVE-2025-38066: Linux kernel · dm cache: prevent BUG_ON by blocking retries on failed device resumes

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f3128e3074e8af565cc6a66fe3384a56df87f803 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 21:04 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in f3128e3074e8af565cc6a66fe3384a56df87f803, cc80a5cc520939d0a7d071cc4ae4b3c55ef171d0, c614584c2a66b538f469089ac089457a34590c14 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 66a636356647a9be8885c2ce2948de126577698a, < f3128e3074e8af565cc6a66fe3384a56df87f803	Fixed in f3128e3074e8af565cc6a66fe3384a56df87f803
LinuxLinux	Affected ≥ 66a636356647a9be8885c2ce2948de126577698a, < cc80a5cc520939d0a7d071cc4ae4b3c55ef171d0	Fixed in cc80a5cc520939d0a7d071cc4ae4b3c55ef171d0
LinuxLinux	Affected ≥ 66a636356647a9be8885c2ce2948de126577698a, < c614584c2a66b538f469089ac089457a34590c14	Fixed in c614584c2a66b538f469089ac089457a34590c14
LinuxLinux	Affected ≥ 66a636356647a9be8885c2ce2948de126577698a, < c5356a5e80442131e2714d0d26bb110590e4e568	Fixed in c5356a5e80442131e2714d0d26bb110590e4e568
LinuxLinux	Affected ≥ 66a636356647a9be8885c2ce2948de126577698a, < 3986ef4a9b6a0d9c28bc325d8713beba5e67586f	Fixed in 3986ef4a9b6a0d9c28bc325d8713beba5e67586f
LinuxLinux	Affected ≥ 66a636356647a9be8885c2ce2948de126577698a, < 00586b78eeb7c626a14ca13453a1631f88a7cf36	Fixed in 00586b78eeb7c626a14ca13453a1631f88a7cf36

Description

In the Linux kernel, the following vulnerability has been resolved: dm cache: prevent BUG_ON by blocking retries on failed device resumes A cache device failing to resume due to mapping errors should not be retried, as the failure leaves a partially initialized policy object. Repeating the resume operation risks triggering BUG_ON when reloading cache mappings into the incomplete policy object. Reproduce steps: 1. create a cache metadata consisting of 512 or more cache blocks, with some mappings stored in the first array block of the mapping array. Here we use cache_restore v1.0 to build the metadata. cat <<EOF >> cmeta.xml <superblock uuid="" block_size="128" nr_cache_blocks="512" \ policy="smq" hint_width="4"> <mappings> <mapping cache_block="0" origin_block="0" dirty="false"/> </mappings> </superblock> EOF dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2 dmsetup remove cmeta 2. wipe the second array block of the mapping array to simulate data degradations. mapping_root=$(dd if=/dev/sdc bs=1c count=8 skip=192 \ 2>/dev/null | hexdump -e '1/8 "%u\n"') ablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \ 2>/dev/null | hexdump -e '1/8 "%u\n"') dd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$ablock 3. try bringing up the cache device. The resume is expected to fail due to the broken array block. dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 65536 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dmsetup create cache --notable dmsetup load cache --table "0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" dmsetup resume cache 4. try resuming the cache again. An unexpected BUG_ON is triggered while loading cache mappings. dmsetup resume cache Kernel logs: (snip) ------------[ cut here ]------------ kernel BUG at drivers/md/dm-cache-policy-smq.c:752! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 332 Comm: dmsetup Not tainted 6.13.4 #3 RIP: 0010:smq_load_mapping+0x3e5/0x570 Fix by disallowing resume operations for devices that failed the initial attempt.

References

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