Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-05-06T00:00:00 kernel: ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data() 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CWE-1284

In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data() On the receive path, __ioam6_fill_trace_data() uses trace->nodelen to decide how much data to write for each node. It trusts this field as-is from the incoming packet, with no consistency check against trace->type (the 24-bit field that tells which data items are present). A crafted packet can set nodelen=0 while setting type bits 0-21, causing the function to write ~100 bytes past the allocated region (into skb_shared_info), which corrupts adjacent heap memory and leads to a kernel panic. Add a shared helper ioam6_trace_compute_nodelen() in ioam6.c to derive the expected nodelen from the type field, and use it: - in ioam6_iptunnel.c (send path, existing validation) to replace the open-coded computation; - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose nodelen is inconsistent with the type field, before any data is written. Per RFC 9197, bits 12-21 are each short (4-octet) fields, so they are included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to 0xff1ffc00).

A flaw was found in the Linux kernel's IPv6 In-situ Operations, Administration, and Maintenance (IOAM) functionality. A remote attacker can send a specially crafted packet that manipulates the `nodelen` field while processing trace data. This manipulation leads to a heap buffer overflow, causing approximately 100 bytes to be written past the allocated memory region. This memory corruption can result in a kernel panic, effectively leading to a Denial of Service (DoS) for the affected system.

Red Hat Enterprise Linux 10 Affected kernel Red Hat Enterprise Linux 6 Under investigation kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Not affected kernel Red Hat Enterprise Linux 9 Not affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-43186 https://nvd.nist.gov/vuln/detail/CVE-2026-43186 https://lore.kernel.org/linux-cve-announce/2026050640-CVE-2026-43186-4c1f@gregkh/T