CVE-2021-47293 net/sched: act_skbmod: Skip non-Ethernet packets
A flaw in the Linux kernel's skbmod action allows silent packet corruption when applied to non-Ethernet interfaces, potentially causing 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-2021-47293?
CVE-2021-47293 is a high-severity memory corruption vulnerability in Linux kernel, published on 21 May 2024. 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: act_skbmod: Skip non-Ethernet packets
Currently tcf_skbmod_act() assumes that packets use Ethernet as their L2 protocol, which is not always the case. As an example, for CAN devices:
$ ip link add dev vcan0 type vcan $ ip link set up vcan0 $ tc qdisc add dev vcan0 root handle 1: htb $ tc filter add dev vcan0 parent 1: protocol ip prio 10 \ matchall action skbmod swap mac
Doing the above silently corrupts all the packets. Do not perform skbmod actions for non-Ethernet packets.
Which versions are affected by CVE-2021-47293?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47293?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2021-47293 being exploited?
There is no known exploitation of CVE-2021-47293 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47293, GHSA-qqw5-j897-27cf, UBUNTU-CVE-2021-47293.