CVE-2026-63920

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An unprivileged slab-out-of-bounds read exists in the Linux kernel. The ip6 datagram recv specific ctl() function trusts the on-wire hdrlen byte when computing the length for put cmsg(), but this length is only validated during the initial parsing phase. An nftables payload-write expression can rewrite the hdrlen after parsing but before the socket buffer reaches recvmsg. This allows the put cmsg() function to read up to 2040 bytes from an 8-byte header. This issue is reachable from an unprivileged user namespace.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.