CVE-2025-38191 [Medium] | Security Vulnerability in Linux Kernel

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().

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-30	0.02%	0.08%	+0.06%
2	2025-07-05	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-30

0.02%

0.08%

+0.06%

2025-07-05

—

0.02%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.5

3.1

MEDIUM

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

[email protected]

OS Trackers for CVE-2025-38191

vendor	priority	summary	link
`debian`	unimportant	CVE-2025-38191 unimportant priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6.	https://security-tracker.debian.org/tracker/CVE-2025-38191
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2025-38191
`suse`	medium	CVE-2025-38191 severity moderate: SUSE including 26 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 281 product×package rows across 55 product lines (SLES-LTSS-TERADATA 15 SP2, SUSE Linux Enterprise High Availability Extension 15 SP7, … (55 product lines)): Known Not Affected 281.	https://www.suse.com/security/cve/CVE-2025-38191/
`ubuntu`	medium	CVE-2025-38191 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, ignored 211, released 138, needed 34, not-affected 20, needs-triage 2, pending 1.	https://ubuntu.com/security/CVE-2025-38191

Affected software / configurations for CVE-2025-38191

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 5.15, < 6.1.142	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.2, < 6.6.95	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.7, < 6.12.35	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.13, < 6.15.4	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.16	cpe:2.3:o:linux:linux_kernel:6.16:rc1::::::
linux	linux_kernel	6.16	cpe:2.3:o:linux:linux_kernel:6.16:rc2::::::
debian	debian_linux	11.0	cpe:2.3:o:debian:debian_linux:11.0:::::::*

References for CVE-2025-38191

URL	Tags
https://git.kernel.org/stable/c/076f1adefb9837977af7ed233883842ddc446644	Patch
https://git.kernel.org/stable/c/0902625a24eea7fdc187faa5d97df244d159dd6e	Patch
https://git.kernel.org/stable/c/1193486dffb7432a09f57f5d09049b4d4123538b	Patch
https://git.kernel.org/stable/c/281afc52e2961cd5dd8326ebc9c5bc40904c0468	Patch
https://git.kernel.org/stable/c/7ac5b66acafcc9292fb935d7e03790f2b8b2dc0e	Patch
https://www.zerodayinitiative.com/advisories/ZDI-25-610/	Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html	Third Party Advisory

URL

CVE-2025-38191 | ksmbd: fix null pointer dereference in destroy_previous_session

Exploit prediction scoring system (EPSS) score for CVE-2025-38191

Common vulnerability scoring system (CVSS) metrics for CVE-2025-38191

Weakness enumeration for CVE-2025-38191

OS Trackers for CVE-2025-38191

Affected software / configurations for CVE-2025-38191

References for CVE-2025-38191