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Fencer Vulns
medium 5.5

CVE-2026-46132 json

net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo

published 2026-05-28 5 mo ago modified 2026-11-06 2 d ago also EUVD-2026-32891

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.88, 6.18.30, 7.0.7, 7.1
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.88-1
  • linux Debian 14 7.0.7-1

debian advisories DEBIAN-CVE-2026-46132

  • linux Ubuntu 22.04 LTS 5.15.0-186.196
  • linux Ubuntu 24.04 LTS 6.8.0-136.136
  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72

ubuntu advisories UBUNTU-CVE-2026-46132

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
  • kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
  • kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.37.1
  • kernel-rt Linux Micro 6.2 6.12.0-160000.37.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1

suse advisories SUSE-SU-2026:23244-1SUSE-SU-2026:23241-1SUSE-SU-2026:23194-1SUSE-SU-2026:23193-1SUSE-SU-2026:23237-1SUSE-SU-2026:23068-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.37.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.37.1

opensuse advisories openSUSE-SU-2026:21555-1openSUSE-SU-2026:10954-1

  • kernel Azure Linux 3.0 6.6.141.1-1

azure linux advisories AZL-88851

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-46132 updated cvss 5.5

kernel: net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-26-295-11 updated cvss 0.0

Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.7 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.7
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 d ago

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-908 Use of Uninitialized Resource
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.