CVE-2026-43186
Description
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.
Statement
A crafted IPv6 IOAM Pre-allocated Trace option can make the receive path trust an inconsistent nodelen value while type bits request more trace data than the allocated area can hold. This can cause __ioam6_fill_trace_data to write about 100 bytes past the IOAM trace area into adjacent heap memory such as skb_shared_info, leading to kernel memory corruption and panic. For the CVSS the PR:N is used because a packet sender does not need credentials on the victim when IPv6 IOAM processing and a matching namespace are configured. The issue is network reachable under IOAM deployment preconditions only. Impact is at least remote denial of service via kernel crash, and worst case may allow confidentiality or integrity impact because the primitive is a heap out-of-bounds write in a packet receive path. However, practical attack exposure is limited because no exploit primitive beyond denial of service has been demonstrated. The bug is specific to IPv6 IOAM processing, which is not commonly deployed and is typically disabled by default on most general-purpose servers. Systems that do not enable IOAM processing on the receive path are generally not reachable through this issue.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 9.8 |
| Attack Vector | Adjacent Network | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
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