CVE-2026-89758 — mm/mempolicy: skip non-present PMDs when queueing folios
In the Linux kernel, the following vulnerability has been resolved: mm/mempolicy: skip non-present PMDs when queueing folios Patch series "mm: handle device-private PMDs in walk callbacks", v3. Since commit 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations") a PMD may hold a device-private swap entry whenever an HMM-based GPU driver migrates an anonymous THP folio to device memory via migrate_vma_pages(). pmd_trans_huge_lock() succeeds for such PMDs (pmd_is_huge() returns true for any non-present, non-none huge PMD), so several MM walk callbacks that used to assume present THP or migration entry are now reachable with a device-private PMD. The results range from a VM_BUG_ON() firing on debug kernels, to an oops on a bogus vmemmap dereference, to silently isolating an unrelated live folio from LRU in the aliasing case. This patch (of 3): queue_folios_pmd() is called under pmd_trans_huge_lock(), whose pmd_is_huge() check returns true for any non-present, non-none PMD softleaf. Passing such a PMD to pmd_folio() treats the softleaf encoding as a hardware PFN and can return a bogus folio pointer. Mirror queue_folios_pte_range(): handle non-present entries before looking up a folio. Keep migration entries counted as failures, but skip other non-present PMDs such as device-private entries. Potential trigger: an HMM-based GPU driver migrates an anonymous THP folio to device memory via migrate_vma_pages(), leaving a device-private PMD. Userspace then calls mbind(), migrate_pages() or set_mempolicy_home_node() on that range.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+1
- Technical severity (high)+6
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.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
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).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
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 |
|---|---|---|---|---|---|
| 7.8 | CVSS 3.1 | High | 1.8 | 5.9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database |
| 7.8 | CVSS 3.1 | High | — | — | Linux via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) 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.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- Record published
- CVSS changed · 7.8
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
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- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 1d
- Unknown CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 2d
- Unknown CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 2d
- Unknown CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 2d
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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 fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No CWE classification.
- 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-2026-89758 is "mm/mempolicy: skip non-present PMDs when queueing folios", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. EPSS 0.17% 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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