CVE-2025-37947: ksmbd: prevent out-of-bounds stream writes by validating *pos

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-05-20 · updated 2026-07-30
Weakness: CWE-787

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: prevent out-of-bounds stream writes by validating *pos ksmbd_vfs_stream_write() did not validate whether the write offset (*pos) was within the bounds of the existing stream data length (v_len). If *pos was greater than or equal to v_len, this could lead to an out-of-bounds memory write. This patch adds a check to ensure *pos is less than v_len before proceeding. If the condition fails, -EINVAL is returned.

Affected products

Debian Linux: 11.0
Linux kernel: from 5.15 before 6.1.139; from 6.2 before 6.6.91; from 6.7 before 6.12.29; from 6.13 before 6.14.7; 6.15-rc1, 6.15-rc2, 6.15-rc3, 6.15-rc4, 6.15-rc5 — fixed in 6.1.139, 6.12.29, 6.14.7, 6.6.91

How to fix

Upgrade to a fixed version: Linux kernel 6.1.139, 6.12.29, 6.14.7, 6.6.91. Check the vendor advisory for mitigations.

References

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