Medium Logic error

CVE-2026-31466 — mm/huge_memory: fix folio isn't locked in softleaf_to_folio()

In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: fix folio isn't locked in softleaf_to_folio() On arm64 server, we found folio that get from migration entry isn't locked in softleaf_to_folio(). This issue triggers when mTHP splitting and zap_nonpresent_ptes() races, and the root cause is lack of memory barrier in softleaf_to_folio(). The race is as follows: CPU0 CPU1 deferred_split_scan() zap_nonpresent_ptes() lock folio split_folio() unmap_folio() change ptes to migration entries __split_folio_to_order() softleaf_to_folio() set flags(including PG_locked) for tail pages folio = pfn_folio(softleaf_to_pfn(entry)) smp_wmb() VM_WARN_ON_ONCE(!folio_test_locked(folio)) prep_compound_page() for tail pages In __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages are visible before the tail page becomes non-compound. smp_wmb() should be paired with smp_rmb() in softleaf_to_folio(), which is missed. As a result, if zap_nonpresent_ptes() accesses migration entry that stores tail pfn, softleaf_to_folio() may see the updated compound_head of tail page before page->flags. This issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio() because of the race between folio split and zap_nonpresent_ptes() leading to a folio incorrectly undergoing modification without a folio lock being held. This is a BUG_ON() before commit 93976a20345b ("mm: eliminate further swapops predicates"), which in merged in v6.19-rc1. To fix it, add missing smp_rmb() if the softleaf entry is migration entry in softleaf_to_folio() and softleaf_to_page(). [tujinjiang@huawei.com: update function name and comments]

Published Apr 22, 2026 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.1% (30-day exploitation probability)+0
Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.12%

ahead of 2% of scored CVEs · Oct 14, 2026

Affects

Linux

Linux and 1 more

CVSS base

4.7

Medium · 2 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (logic error), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	version 4.5≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b and < 4c5e7f0fcd592801c9cc18f29f80fbee84eb8669≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b and < 8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b and < 7ad1997b9bc8032603df8f091761114479285769≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b and < b8c49ad888892ad7b77062b9c102b799a3e9b4f8≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b and < 7ddcf4a245c1c5a91fdd9698757e3d95179ffe41≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b and < 722cfaf6b31d31123439e67b5deac6b1261a3dea≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b and < f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd and 1 more ≥ e9b61f19858a5d6c42ce2298cf138279375d0d9b and < 426ee10711586617da869c8bb798214965337617	Vulnerable	CVE Program (cve.org) e CISA ADP
Linux	Linux Kernel	version 7.0-rc4version 7.0-rc5≥ 4.5 and < 5.10.253version 7.0-rc3version 7.0-rc2version 7.0-rc1≥ 6.19 and < 6.19.11≥ 6.13 and < 6.18.21 and 4 more ≥ 6.7 and < 6.12.81≥ 6.2 and < 6.6.134≥ 5.16 and < 6.1.168≥ 5.11 and < 5.15.203	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

High

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
4.7	CVSS 3.1	Medium	1.0	3.6	nvd@nist.gov via NIST National Vulnerability Database
4.7	CVSS 3.1	Medium	—	—	GitHub, Inc. via GitHub Security Advisories

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-362 · Race Condition

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.12%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.

endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · linux/linux
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 4.7
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Modified
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Apr 22, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 14, 2026 – Oct 14, 2026
1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

13 on the record

git.kernel.org/stable/c/7ddcf4a245c1c5a91fdd9698757e3d95179ffe41
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/7ad1997b9bc8032603df8f091761114479285769
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/722cfaf6b31d31123439e67b5deac6b1261a3dea
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/4c5e7f0fcd592801c9cc18f29f80fbee84eb8669
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/b8c49ad888892ad7b77062b9c102b799a3e9b4f8
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/426ee10711586617da869c8bb798214965337617
Patch, NIST National Vulnerability Database
nvd.nist.gov/vuln/detail/CVE-2026-31466
GitHub Security Advisories
cert-portal.siemens.com/productcert/html/ssa-082556.html
NIST National Vulnerability Database
cert-portal.siemens.com/productcert/html/ssa-457936.html
NIST National Vulnerability Database
cert-portal.siemens.com/productcert/html/ssa-019113.html
NIST National Vulnerability Database
github.com/advisories/GHSA-j7cp-5j3g-7q5w
GitHub Security Advisories

Elsewhere on this site

Linux
every CVE for this vendor

Logic error
same class

CWE-362
other pages naming this weakness

Related CVEs (same products)

Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 9h
Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 9h
Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CISA SSVC assessment.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-31466 is "mm/huge_memory: fix folio isn't locked in softleaf_to_folio()", rated Medium. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.7 describes technical severity. EPSS 0.12% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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