In the Linux kernel, the following vulnerability has been resolved:
mm/page_vma_mapped: fix device-private PMD handling
Commit 65edfda6f3f2 ("mm/rmap: extend rmap and migration support
device-private entries") introduced the concept of device-private PMD
entries, but did not correctly update the rmap walk code to account for
them.
As a result, when page_vma_mapped_walk() encounters device-private PMD
entries, it takes no action other than to acquire the PMD lock and exit.
However this is highly problematic for two reasons - firstly, device
private entries possess a PFN so check_pmd() needs to be called to ensure
an overlapping PFN range.
Secondly, and more importantly, if PVMW_MIGRATION is set the caller
assumes the returned entry is a migration entry, resulting in memory
corruption when the caller tries to interpret the device private entry as
such.
In addition, commit 146287290023 ("mm/huge_memory: implement
device-private THP splitting") allowed device private PMDs to be split
like THP mappings, but again did not update this code path.
As a result, we might race a PMD split prior to acquiring the PMD lock.
This patch addresses all of these issues by invoking check_pmd(), ensuring
PMVW_MIGRATION is not set and checks whether a split raced us we do for
PMD THP and migration entries.
Instead of checking for a subset of the cases after taking the pmd_lock(),
put device-private along with pmd_trans_huge() and
pmd_is_migration_entry(). Also remove thp_migration_supported() as it is
already guarded by pmd_is_migration_entry().
[[email protected]: fix Raspberry Pi 1 build, per David]
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.8 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 2026-10-19). 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: 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.
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