CVE-2026-68086 — mm/khugepaged: write all dirty file folios when collapsing
In the Linux kernel, the following vulnerability has been resolved: mm/khugepaged: write all dirty file folios when collapsing [There is no upstream commit, as this code was removed by upstream commit 044925f9b565 ("mm: fs: remove filemap_nr_thps*() functions and their users")] As-is, khugepaged and writable-file opening exclude each other. A file cannot be open writeable and have THPs (because the filesystem is not aware of them). khugepaged will never collapse file pages for files that are opened writeable. On an open(O_RDWR/O_WRONLY), the page cache for that particular file is dropped. This is fine because nothing could've been dirtied. However, there is an edge-case: collapse_file() might not be able to coexist with concurrent writers, but it can coexist with dirty folios (from previous writers). Therefore, the following can happen: open(file, O_RDWR) write(file) close(file) madvise(file_mapping, MADV_COLLAPSE, some non-dirty range) open(file, O_RDWR) nr_thps > 0 truncate_inode_pages() /* THPs are cleared out, but so are the dirty folios */ When this edge-case happens, there is data loss, as the dirty folios are fully discarded. Fix it by fully writing back the page cache (and waiting) when collapsing file THPs. Doing so provides the guarantee that no dirty folio will be observed while there are active THPs. To fully ensure this is safe, the invalidate_lock needs to be held while doing the writeout, so that do_dentry_open()'s page cache truncation excludes this write-and-wait. As a side effect, move the nr_thps counter bumping outside the i_pages lock. This is correct since the counter itself is an atomic_t and the producer <-> consumer correctness is provided by a full memory barrier: smp_mb() in collapse_file()/memory barrier implied by full ordering in get_write_access() -> atomic_inc_unless_negative().
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
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.
EPSS over time FIRST
Oct 15, 2026 → Oct 30, 2026 · 15 reading(s) · max 0.15%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Not enough vector or weakness data: use the affected application’s logs as a starting point.
Timeline
What happened to this CVE, newest first.
- 2026
- Record published
- Affected products added · linux/linux
- 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
1 on the record
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-99216 Drivers: hv: Don't reset VMBus connection state on error/exit paths 3d
- Unknown CVE-2026-99215 power: supply: core: prevent unregistering a power supply while a callback runs 3d
- Unknown CVE-2026-99207 scsi: target: Disable interrupts while holding delayed_cmd_lock 3d
- Unknown CVE-2026-99208 drm/xe/oa: Zero OA buffer at allocation 3d
- Unknown CVE-2026-99209 drm/xe: skip eviction of a BO with no resource 3d
- Unknown CVE-2026-99210 accel/rocket: clear rdev on device init failure 3d
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 CVSS score published by NVD, the CNA, CISA or GitHub so far.
- 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-2026-68086 is "mm/khugepaged: write all dirty file folios when collapsing", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.15% 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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