CVE-2025-38191: debian linux Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix null pointer dereference in destroy_previous_session If client set ->PreviousSessionId on kerberos session setup stage, NULL pointer dereference error will happen. Since sess->user is not set yet, It can pass the user argument as NULL to destroy_previous_session. sess->user will be set in ksmbd_krb5_authenticate(). So this patch move calling destroy_previous_session() after ksmbd_krb5_authenticate().

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.15 — 6.1.142
linux	linux_kernel	6.2 — 6.6.95
linux	linux_kernel	6.7 — 6.12.35
linux	linux_kernel	6.13 — 6.15.4
linux	linux_kernel	All
linux	linux_kernel	All
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/076f1adefb9837977af7ed233883842ddc446644 https://git.kernel.org/stable/c/0902625a24eea7fdc187faa5d97df244d159dd6e https://git.kernel.org/stable/c/1193486dffb7432a09f57f5d09049b4d4123538b https://git.kernel.org/stable/c/281afc52e2961cd5dd8326ebc9c5bc40904c0468 https://git.kernel.org/stable/c/7ac5b66acafcc9292fb935d7e03790f2b8b2dc0e

Other References

https://www.zerodayinitiative.com/advisories/ZDI-25-610/ https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html

Frequently Asked Questions

What is CVE-2025-38191? +

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix null pointer dereference in destroy_previous_session If client set ->PreviousSessionId on kerberos session setup stage, NULL pointer dereference error will happen. Since sess->user is not set yet, It can pass the user argument as NULL to destroy_previous_session. sess->user will be set in ksmbd_krb5_authenticate(). So this patch move calling destroy_previous_session() after ksmbd_krb5_authenticate(). It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-38191? +

CVE-2025-38191 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-38191? +

CVE-2025-38191 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-38191? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2025-38191