Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-05-28T00:00:00 kernel: net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CWE-908

In the Linux kernel, the following vulnerability has been resolved: net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo rtnl_fill_vfinfo() declares struct ifla_vf_broadcast on the stack without initialisation: struct ifla_vf_broadcast vf_broadcast; The struct contains a single fixed 32-byte field: /* include/uapi/linux/if_link.h */ struct ifla_vf_broadcast { __u8 broadcast[32]; }; The function then copies dev->broadcast into it using dev->addr_len as the length: memcpy(vf_broadcast.broadcast, dev->broadcast, dev->addr_len); On Ethernet devices (the overwhelming majority of SR-IOV NICs) dev->addr_len is 6, so only the first 6 bytes of broadcast[] are written. The remaining 26 bytes retain whatever was previously on the kernel stack. The full struct is then handed to userspace via: nla_put(skb, IFLA_VF_BROADCAST, sizeof(vf_broadcast), &vf_broadcast) leaking up to 26 bytes of uninitialised kernel stack per VF per RTM_GETLINK request, repeatable. The other vf_* structs in the same function are explicitly zeroed for exactly this reason - see the memset() calls for ivi, vf_vlan_info, node_guid and port_guid a few lines above. vf_broadcast was simply missed when it was added. Reachability: any unprivileged local process can open AF_NETLINK / NETLINK_ROUTE without capabilities and send RTM_GETLINK with an IFLA_EXT_MASK attribute carrying RTEXT_FILTER_VF. The kernel walks each VF and emits IFLA_VF_BROADCAST, leaking 26 bytes of stack per VF per request. Stack residue at this call site can include return addresses and transient sensitive data; KASAN with stack instrumentation, or KMSAN, will flag the nla_put() when reproduced. Zero the on-stack struct before the partial memcpy, matching the existing pattern used for the other vf_* structs in the same function.

A flaw was found in the Linux kernel's rtnetlink component. The `rtnl_fill_vfinfo` function declares a structure on the stack without full initialization. When processing RTM_GETLINK requests with a specific attribute, an unprivileged local process can exploit this to read up to 26 bytes of uninitialized kernel stack memory. This information disclosure can expose sensitive data, including return addresses and other transient data, potentially aiding further attacks.

Red Hat Enterprise Linux 10 Affected kernel Red Hat Enterprise Linux 6 Out of support scope kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Affected kernel Red Hat Enterprise Linux 8 Affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel Red Hat Enterprise Linux 9 Affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-46132 https://nvd.nist.gov/vuln/detail/CVE-2026-46132 https://lore.kernel.org/linux-cve-announce/2026052817-CVE-2026-46132-9410@gregkh/T