What’s Vulnerable › Vulnerabilities

CVE-2025-40103: smb: client: Fix refcount leak for cifs_sb_tlink

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-10-30 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: Fix refcount leak for cifs_sb_tlink Fix three refcount inconsistency issues related to `cifs_sb_tlink`. Comments for `cifs_sb_tlink` state that `cifs_put_tlink()` needs to be called after successful calls to `cifs_sb_tlink()`. Three calls fail to update refcount accordingly, leading to possible resource leaks.

Affected products

• Linux kernel: 3.7 — fixed in 6.18

How to fix

Upgrade to a fixed version: Linux kernel 6.18. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/790282abe9d805f08618c1c24ea2529e7259b692
• https://git.kernel.org/stable/c/896bb31e1416f582503db1350cf1bd10dc64e5a6
• https://git.kernel.org/stable/c/c2b77f42205ef485a647f62082c442c1cd69d3fc
• https://git.kernel.org/stable/c/d3c8ea197055c260119a13360e8202a27e53e1e4
• https://git.kernel.org/stable/c/d7dd034c14928306db1b46be277ae439b84dacf9
• https://git.kernel.org/stable/c/e15605b68b490186da2ad8029c0351a9cfb0b9af

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