How severe is CVE-2025-39745?

This vulnerability has a CVSS score of (Unknown severity).

How difficult is it to exploit CVE-2025-39745?

Exploit difficulty: HARD. Estimated time to exploit: > 4 hours. Required skills: Advanced security expertise.

CVE-2025-39745 - YourPassGen

In the Linux kernel, the following vulnerability has been resolved:

rcutorture: Fix rcutorture_one_extend_check() splat in RT kernels

For built with CONFIG_PREEMPT_RT=y kernels, running rcutorture
tests resulted in the following splat:

[ 68.797425] rcutorture_one_extend_check during change: Current 0x1 To add 0x1 To remove 0x0 preempt_count() 0x0
[ 68.797533] WARNING: CPU: 2 PID: 512 at kernel/rcu/rcutorture.c:1993 rcutorture_one_extend_check+0x419/0x560 [rcutorture]
[ 68.797601] Call Trace:
[ 68.797602]
[ 68.797619] ? lockdep_softirqs_off+0xa5/0x160
[ 68.797631] rcutorture_one_extend+0x18e/0xcc0 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797646] ? local_clock+0x19/0x40
[ 68.797659] rcu_torture_one_read+0xf0/0x280 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797678] ? __pfx_rcu_torture_one_read+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797804] ? __pfx_rcu_torture_timer+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797815] rcu-torture: rcu_torture_reader task started
[ 68.797824] rcu-torture: Creating rcu_torture_reader task
[ 68.797824] rcu_torture_reader+0x238/0x580 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797836] ? kvm_sched_clock_read+0x15/0x30

Disable BH does not change the SOFTIRQ corresponding bits in
preempt_count() for RT kernels, this commit therefore use
softirq_count() to check the if BH is disabled.

Related CVE by CWE

No related CWE found.

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How to fix CVE-2025-39745

CVE-2025-39745 is a unknown severity vulnerability affecting the affected product.

Description: In the Linux kernel, the following vulnerability has been resolved: rcutorture: Fix rcutorture_one_extend_check() splat in RT kernels For built with CONFIG_PREEMPT_RT=y kernels, running rcutorture tests resulted in the following splat: [ 68.797425] rcutorture_one_extend_check during change: Current 0x1 To add 0x1 To remove 0x0 preempt_count() 0x0 [ 68.797533] WARNING: CPU: 2 PID: 512 at kernel/rcu/rcutorture.c:1993 rcutorture_one_extend_check+0x419/0x560 […]

Exploit Difficulty: HARD
⏱️ Time to exploit: > 4 hours
🛠️ Required skills: Advanced security expertise
💰 Public exploits: Rare or not public

How to Fix:

1 Identify affected systems

- Check if you're running the affected product

2 Immediate actions

- Update to the latest patched version
- If patching is not immediately possible: restrict network exposure, apply least-privilege access

3 Verification

- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)

4 Long-term prevention

- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations

Full CVE details

Exploit Difficulty Assessment

HARD

⏱️ Time to Exploit: > 4 hours

🛠️ Skills Required: Advanced security expertise

💰 Public Exploits: Rare or not public

Vulnerability Timeline

Sep 11, 2025

Vulnerability Published

CVE details first published to NVD database

Nov 12, 2025

Imported to Database

Added to this CVE tracking system

Detection Rules & IOCs

No specific detection rules generated for this vulnerability type.

No vendor/product data available.

No related CVEs found (no vendor/product data available).