CVE-2025-38115 net_sched: sch_sfq: fix a potential crash on gso_skb handling
A local attacker can cause a kernel crash in the SFQ network scheduler by triggering a null pointer dereference during GSO packet handling.
- 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-2025-38115?
CVE-2025-38115 is a high-severity vulnerability in Debian Debian Linux, published on 3 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: fix a potential crash on gso_skb handling
SFQ has an assumption of always being able to queue at least one packet.
However, after the blamed commit, sch->q.len can be inflated by packets in sch->gso_skb, and an enqueue() on an empty SFQ qdisc can be followed by an immediate drop.
Fix sfq_drop() to properly clear q->tail in this situation.
ip netns add lb ip link add dev to-lb type veth peer name in-lb netns lb ethtool -K to-lb tso off # force qdisc to requeue gso_skb ip netns exec lb ethtool -K in-lb gro on # enable NAPI ip link set dev to-lb up ip -netns lb link set dev in-lb up ip addr add dev to-lb 192.168.20.1/24 ip -netns lb addr add dev in-lb 192.168.20.2/24 tc qdisc replace dev to-lb root sfq limit 100
ip netns exec lb netserver
netperf -H 192.168.20.2 -l 100 & netperf -H 192.168.20.2 -l 100 & netperf -H 192.168.20.2 -l 100 & netperf -H 192.168.20.2 -l 100 &
Weakness: CWE-401
Which versions are affected by CVE-2025-38115?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38115?
Apply the vendor's patch.
Is CVE-2025-38115 being exploited?
There is no known exploitation of CVE-2025-38115 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-64580, BELL-CVE-2025-38115, DEBIAN-CVE-2025-38115, GHSA-9gqr-9337-3jr8, ROOT-OS-DEBIAN-11-CVE-2025-38115, ROOT-OS-DEBIAN-12-CVE-2025-38115 and 3 more.