VulnerabilityPublished 18 Oct 2026

CVE-2026-98844: Linux kernel · netfs: clear post-EOF pagecache when extending a file via write

Source GCVE Database

Authoritative record:CVE-2026-98844· Medium

Not known to be exploited · fixed in f8f7d86b3537e885ee620898a38b749fba8a8456 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f8f7d86b3537e885ee620898a38b749fba8a8456, a7036a73671fc83d299bc770710fe996d9fef9ca, 98f6a4589e0f5f6cf819b8dd45605efc481c06ce +1

Exploitation evidence

Disclosed: evidence found.
CVE published 18 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.

ghsa-vjf5-4hx8-9557

What to do

Upgrade Linux kernel to f8f7d86b3537e885ee620898a38b749fba8a8456, a7036a73671fc83d299bc770710fe996d9fef9ca, 98f6a4589e0f5f6cf819b8dd45605efc481c06ce or 69bf14300b50631e7c2271289d347bbd1b19a06c.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 153a9961b551101cd38e94e26cd92fbfd198b19b, < f8f7d86b3537e885ee620898a38b749fba8a8456	Fixed in f8f7d86b3537e885ee620898a38b749fba8a8456
LinuxLinux	Affected ≥ 153a9961b551101cd38e94e26cd92fbfd198b19b, < a7036a73671fc83d299bc770710fe996d9fef9ca	Fixed in a7036a73671fc83d299bc770710fe996d9fef9ca
LinuxLinux	Affected ≥ 153a9961b551101cd38e94e26cd92fbfd198b19b, < 98f6a4589e0f5f6cf819b8dd45605efc481c06ce	Fixed in 98f6a4589e0f5f6cf819b8dd45605efc481c06ce
LinuxLinux	Affected ≥ 153a9961b551101cd38e94e26cd92fbfd198b19b, < 69bf14300b50631e7c2271289d347bbd1b19a06c	Fixed in 69bf14300b50631e7c2271289d347bbd1b19a06c
LinuxLinux	Affected =6.8	Fixed in–
Red Hatredhat/kernel`pkg:rpm/redhat/kernel`Other threats	Affected =6.8	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel netfs subsystem. Users and administrators should apply the official kernel updates that include this patch to ensure the issue is resolved. Since this is a kernel-level fix, upgrading to a kernel version containing this patch is the recommended remediation. Patch status is not explicitly stated in the provided data; therefore, check the vendor or Linux kernel advisory for the exact fixed version and update accordingly.

Description

A vulnerability in the Linux kernel's netfs subsystem related to handling pagecache beyond the end-of-file (EOF) during file extension via write has been resolved. The issue involved stale data remaining in the pagecache after extending a file, which could lead to incorrect data exposure or corruption. The fix ensures that the tail of the folio straddling the EOF is zeroed before an extending write, preventing stale data from persisting. The patch also handles concurrency and writeback synchronization to avoid data loss or corruption during concurrent writes.

Impact

The vulnerability could result in stale or unintended data being exposed or written beyond the EOF during file extension operations, potentially leading to data corruption or leakage of previously written data through memory-mapped files. This affects the integrity and confidentiality of file data handled by netfs in the Linux kernel. No known exploits in the wild have been reported.

Summary

The Linux kernel netfs vulnerability (CVE-2026-98844) involved improper clearing of the post-EOF pagecache when extending a file via write operations. Specifically, stale data could remain in the pagecache if dirty data was previously written through an mmapped region, as neither buffered nor direct I/O write paths cleared this stale cache. The fix zeroes the tail of the folio overlapping the EOF before extending writes, ensuring no stale data is exposed. It also manages concurrent extending writes by re-reading the file size under folio lock and clamps zeroing accordingly, and waits for any ongoing writeback to complete before zeroing. This prevents data races and ensures data integrity during concurrent file extension and writeback operations. The fix includes a helper function to handle cases where exclusive locks are held for file resize operations, used by the CIFS client to address related issues.

References

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