CVE-2025-39780 [Medium] | Security Vulnerability in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: sched/ext: Fix invalid task state transitions on class switch When enabling a sched_ext scheduler, we may trigger invalid task state transitions, resulting in warnings like the following (which can be easily reproduced by running the hotplug selftest in a loop): sched_ext: Invalid task state transition 0 -> 3 for fish[770] WARNING: CPU: 18 PID: 787 at kernel/sched/ext.c:3862 scx_set_task_state+0x7c/0xc0 ... RIP: 0010:scx_set_task_state+0x7c/0xc0 ... Call Trace: <TASK> scx_enable_task+0x11f/0x2e0 switching_to_scx+0x24/0x110 scx_enable.isra.0+0xd14/0x13d0 bpf_struct_ops_link_create+0x136/0x1a0 __sys_bpf+0x1edd/0x2c30 __x64_sys_bpf+0x21/0x30 do_syscall_64+0xbb/0x370 entry_SYSCALL_64_after_hwframe+0x77/0x7f This happens because we skip initialization for tasks that are already dead (with their usage counter set to zero), but we don't exclude them during the scheduling class transition phase. Fix this by also skipping dead tasks during class swiching, preventing invalid task state transitions.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-09-12	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-09-12

—

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-2025-39780

vendor	priority	summary	link
`debian`	unimportant	CVE-2025-39780 unimportant priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2025-39780
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2025-39780
`suse`	medium	CVE-2025-39780 severity moderate: SUSE including 26 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 317 product×package rows across 60 product lines (SLES-LTSS-TERADATA 15 SP2, SUSE Linux Enterprise High Availability Extension 15 SP3, … (60 product lines)): Known Not Affected 317.	https://www.suse.com/security/cve/CVE-2025-39780/
`ubuntu`	medium	CVE-2025-39780 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1414 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): DNE 1017, ignored 175, not-affected 129, released 88, needed 3, needs-triage 2.	https://ubuntu.com/security/CVE-2025-39780

Affected software / configurations for CVE-2025-39780

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 6.12, < 6.12.44	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.13, < 6.16.4	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.17	cpe:2.3:o:linux:linux_kernel:6.17:rc1::::::
linux	linux_kernel	6.17	cpe:2.3:o:linux:linux_kernel:6.17:rc2::::::

References for CVE-2025-39780

URL	Tags
https://git.kernel.org/stable/c/6a32cbe95029ebe21cc08349fd7ef2a3d32d2043	Patch
https://git.kernel.org/stable/c/786f6314604b34c3e7de5f733f4e08e35c448a50	Patch
https://git.kernel.org/stable/c/ddf7233fcab6c247379d0928d46cc316ee122229	Patch

URL

CVE-2025-39780 | sched/ext: Fix invalid task state transitions on class switch

Exploit prediction scoring system (EPSS) score for CVE-2025-39780

Common vulnerability scoring system (CVSS) metrics for CVE-2025-39780

Weakness enumeration for CVE-2025-39780

OS Trackers for CVE-2025-39780

Affected software / configurations for CVE-2025-39780

References for CVE-2025-39780