CVE-2025-38193 net_sched: sch_sfq: reject invalid perturb period
An integer overflow in the Linux kernel's SFQ scheduler allows triggering a race condition, potentially leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38193?
CVE-2025-38193 is a high-severity vulnerability in Debian Debian Linux, published on 4 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net_sched: sch_sfq: reject invalid perturb period
Gerrard Tai reported that SFQ perturb_period has no range check yet, and this can be used to trigger a race condition fixed in a separate patch.
We want to make sure ctl->perturb_period * HZ will not overflow and is positive.
tc qd add dev lo root sfq perturb -10 # negative value : error Error: sch_sfq: invalid perturb period.
tc qd add dev lo root sfq perturb 1000000000 # too big : error Error: sch_sfq: invalid perturb period.
tc qd add dev lo root sfq perturb 2000000 # acceptable value tc -s -d qd sh dev lo qdisc sfq 8005: root refcnt 2 limit 127p quantum 64Kb depth 127 flows 128 divisor 1024 perturb 2000000sec Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0
Weakness: CWE-190
Which versions are affected by CVE-2025-38193?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38193?
Apply the vendor's patch.
Is CVE-2025-38193 being exploited?
There is no known exploitation of CVE-2025-38193 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-64764, BELL-CVE-2025-38193, DEBIAN-CVE-2025-38193, GHSA-53vw-2fxq-35qf, ROOT-OS-DEBIAN-11-CVE-2025-38193, ROOT-OS-DEBIAN-12-CVE-2025-38193 and 3 more.