CVE-2026-98685: smb: client: discard post-EOF pagecache when extending a file via clone range

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-18 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: discard post-EOF pagecache when extending a file via clone range cifs_remap_file_range() discarded the pagecache only for the folios overlapping the destination region, so when a clone extends the file the folio straddling the old EOF - which may hold data dirtied past EOF through an mmap - was never dropped and became visible as file content once the file was extended. Start the discard at the smaller of fstart and the old EOF. i_size is still old here, so nothing past the old EOF is flushed to the server.

Affected products

Linux kernel: from 6.1.68 before 6.2; from 6.6.7 before 6.7; 6.7 — fixed in 6.2, 6.7, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 6.2, 6.7, 7.3. Check the vendor advisory for mitigations.

References

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