CVE-2022-49197 af_netlink: Fix shift out of bounds in group mask calculation
A shift-out-of-bounds error in the Linux kernel netlink subsystem can cause undefined behavior or crashes when handling high-numbered multicast groups.
- 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-2022-49197?
CVE-2022-49197 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 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:
af_netlink: Fix shift out of bounds in group mask calculation
When a netlink message is received, netlink_recvmsg() fills in the address of the sender. One of the fields is the 32-bit bitfield nl_groups, which carries the multicast group on which the message was received. The least significant bit corresponds to group 1, and therefore the highest group that the field can represent is 32. Above that, the UB sanitizer flags the out-of-bounds shift attempts.
Which bits end up being set in such case is implementation defined, but it's either going to be a wrong non-zero value, or zero, which is at least not misleading. Make the latter choice deterministic by always setting to 0 for higher-numbered multicast groups.
To get information about membership in groups >= 32, userspace is expected to use nl_pktinfo control messages[0], which are enabled by NETLINK_PKTINFO socket option. [0] https://lwn.net/Articles/147608/
The way to trigger this issue is e.g. through monitoring the BRVLAN group:
# bridge monitor vlan & # ip link add name br type bridge
Which produces the following citation:
UBSAN: shift-out-of-bounds in net/netlink/af_netlink.c:162:19 shift exponent 32 is too large for 32-bit type 'int'
Weakness: CWE-190
Which versions are affected by CVE-2022-49197?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-49197?
Apply the vendor's patch.
Is CVE-2022-49197 being exploited?
There is no known exploitation of CVE-2022-49197 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-49197, GHSA-mmh9-qrx9-9x5h, UBUNTU-CVE-2022-49197.