---
id: CVE-2025-39703
title: 'kernel: net, hsr: reject HSR frame if skb can''t hold tag (CVE-2025-39703)'
summary: >-
  A flaw was found in the Linux kernel's High-availability Seamless Redundancy
  (HSR) networking subsystem. This flaw allows an adjacent network attacker or a
  local user to cause a denial of service (DoS) by transmitting malformed HSR
  network…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: vendor
cwe: CWE-1286
vendor: Red Hat
product: Red Hat Enterprise Linux 9
affected:
  - enterprise_linux 10
  - enterprise_linux 9
published: '2025-09-05'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T22:56:06+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39703.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39703.json
  - url: 'https://access.redhat.com/security/cve/CVE-2025-39703'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2393535'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2025-39703'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-39703'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2025090549-CVE-2025-39703-b03b@gregkh/T
  - url: 'https://git.kernel.org/stable/c/8d9bc4a375a1ba05f7dfa0407de8e510ab9bd14d'
  - url: 'https://git.kernel.org/stable/c/3ae272ab523dd6bdc26e879027ed79feac9dd1b3'
  - url: 'https://git.kernel.org/stable/c/b640188b8a6690e685939053c7efdbc7818b5f4e'
  - url: 'https://git.kernel.org/stable/c/b117c41b00902c1a7e24347c405cb82504aeae0b'
  - url: 'https://git.kernel.org/stable/c/acd69b597bd3f76d3b3d322b84082226c00eeaa4'
  - url: 'https://git.kernel.org/stable/c/61009439e4bd8d74e705ee15940760321be91d8a'
  - url: 'https://git.kernel.org/stable/c/7af76e9d18a9fd6f8611b3313c86c190f9b6a5a7'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.00376
epssPercentile: 0.31354
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-15T21:53:38.514386Z'
scores:
  vendor: 6.5
  cna: 9.8
ingestedAt: '2026-10-15T22:48:25.521Z'
---

## Overview

A flaw was found in the Linux kernel's High-availability Seamless Redundancy (HSR) networking subsystem. This flaw allows an adjacent network attacker or a local user to cause a denial of service (DoS) by transmitting malformed HSR network frames with incomplete tags. Due to insufficient packet length validation, processing these frames corrupts internal buffer state, triggering a kernel panic and crashing the system.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39703.json)

**kernel: net, hsr: reject HSR frame if skb can't hold tag** — rated Moderate by Red Hat. Released 2025-09-05, updated 2026-10-16.

Affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9

No fix planned:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9

Not affected:

- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8

## Remediation

Fix deferred

Workarounds / mitigations:

- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.