CVE-2026-98684
In the Linux kernel, the following vulnerability has been resolved: smb: client: flush and commit data before querying allocated ranges The mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for sm…
Overview
CVE-2026-98684 is a known-severity vulnerability. It was published on October 18, 2026.
Technical description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: flush and commit data before querying allocated ranges
The mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for small interior
ranges in smb3_simple_fallocate_range() issues
FSCTL_QUERY_ALLOCATED_RANGES and zero-fills any sub-range the server
reports as an unallocated hole, to force block allocation without
changing file contents.
This is unsafe against Windows servers. Per the Win32 documentation,
FSCTL_QUERY_ALLOCATED_RANGES only reports ranges that *may* contain
nonzero data and is explicitly not coherent with recently written data:
"a call to FSCTL_QUERY_ALLOCATED_RANGES [after writing to a network
file] would not necessarily return a correct list of allocated
regions. To ensure coherency [...] flush the data to the file"
fsx (generic/363) reproduces the resulting corruption against Windows
Server 2022: a range is written, an uncached read returns the data, yet
the next FSCTL_QUERY_ALLOC
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
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Frequently asked questions
What is CVE-2026-98684?
CVE-2026-98684 is a known-severity vulnerability. It was published on October 18, 2026.
How severe is CVE-2026-98684?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2026-98684?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-98684?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-98684 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.