CVE-2025-38006: net: mctp: Don't access ifa_index when missing

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-06-18 · updated 2026-10-30
Weakness: CWE-908

Description

In the Linux kernel, the following vulnerability has been resolved: net: mctp: Don't access ifa_index when missing In mctp_dump_addrinfo, ifa_index can be used to filter interfaces, but only when the struct ifaddrmsg is provided. Otherwise it will be comparing to uninitialised memory - reproducible in the syzkaller case from dhcpd, or busybox "ip addr show". The kernel MCTP implementation has always filtered by ifa_index, so existing userspace programs expecting to dump MCTP addresses must already be passing a valid ifa_index value (either 0 or a real index). BUG: KMSAN: uninit-value in mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128 mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128 rtnl_dump_all+0x3ec/0x5b0 net/core/rtnetlink.c:4380 rtnl_dumpit+0xd5/0x2f0 net/core/rtnetlink.c:6824 netlink_dump+0x97b/0x1690 net/netlink/af_netlink.c:2309

Affected products

Linux kernel: from 5.15 before 6.6.92; from 6.7 before 6.12.30; from 6.13 before 6.14.8; 6.15-rc1, 6.15-rc2, 6.15-rc3, 6.15-rc4, 6.15-rc5, 6.15-rc6 — fixed in 6.6.92, 6.12.30, 6.14.8
Linux: 5.15 — fixed in 6.15

How to fix

Upgrade to a fixed version: Linux kernel 6.6.92, 6.12.30, 6.14.8; Linux 6.15. Check the vendor advisory for mitigations.

References

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