VulnerabilityPublished 28 Oct 2026

CVE-2026-99111: Linux kernel · smb: client: fix data corruption with concurrent writes and O_TRUNC

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in ffa66fdc7d35b890606767c4d2c7ac26b4d90a99 : update Linux kernel when convenient.

Data as of 28 Oct 2026, 10:58 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

Patch: Available – fixed in ffa66fdc7d35b890606767c4d2c7ac26b4d90a99, a8603b52b39f520ea8a34def74c23fba87396d3e, 4d143608a0445443a85c9b29f4c9f8e63d5dbfc9

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to ffa66fdc7d35b890606767c4d2c7ac26b4d90a99, a8603b52b39f520ea8a34def74c23fba87396d3e or 4d143608a0445443a85c9b29f4c9f8e63d5dbfc9.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 110fee6b9bb58a5c50047fc2594d415f741b591e, < ffa66fdc7d35b890606767c4d2c7ac26b4d90a99	Fixed in ffa66fdc7d35b890606767c4d2c7ac26b4d90a99
LinuxLinux	Affected ≥ 110fee6b9bb58a5c50047fc2594d415f741b591e, < a8603b52b39f520ea8a34def74c23fba87396d3e	Fixed in a8603b52b39f520ea8a34def74c23fba87396d3e
LinuxLinux	Affected ≥ 110fee6b9bb58a5c50047fc2594d415f741b591e, < 4d143608a0445443a85c9b29f4c9f8e63d5dbfc9	Fixed in 4d143608a0445443a85c9b29f4c9f8e63d5dbfc9
LinuxLinux	Affected =6.18	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix data corruption with concurrent writes and O_TRUNC cifs_do_truncate() flushes dirty pages with filemap_write_and_wait() and truncates the file on the server, but in the old code both operations ran without holding i_rwsem or invalidate_lock. A concurrent buffered write via netfs_perform_write() -- which only needs i_rwsem shared -- could dirty new pages after the flush but before the local truncation, and those pages would be silently discarded by cifs_setsize() -> truncate_pagecache(). Fix by acquiring inode_lock (exclusive i_rwsem) and filemap_invalidate_lock at the top of cifs_do_truncate(), so the entire flush-truncate-resize sequence is atomic with respect to: - buffered writes (blocked by exclusive i_rwsem, since netfs_start_io_write takes i_rwsem shared), - read page faults (blocked by exclusive invalidate_lock, since filemap_fault takes it shared), - writeback collection (blocked by netfs_wb_begin/netfs_wb_end around the server truncate and local resize, since netfs_writepages also acquires the wb lock).

References

Community reviews

Loading reviews…