---
id: CVE-2026-30871
title: OpenWrt Project is a Linux operating system targeting embedded devices
summary: >-
  OpenWrt Project is a Linux operating system targeting embedded devices. In
  versions prior to 24.10.6 and 25.12.1, the mdns daemon has a Stack-based
  Buffer Overflow vulnerability in the parse_question function. The issue is 
  triggered by …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-121
vendor: openwrt
product: openwrt
affected:
  - openwrt < 24.10.6
  - 'openwrt >= 25.12.0, < 25.12.1'
patched:
  - openwrt 25.12.1
published: '2026-03-19'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T23:17:41.983'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-30871'
references:
  - url: 'https://github.com/openwrt/openwrt/releases/tag/v24.10.6'
    label: security-advisories@github.com
  - url: 'https://github.com/openwrt/openwrt/releases/tag/v25.12.1'
    label: security-advisories@github.com
  - url: 'https://github.com/openwrt/openwrt/security/advisories/GHSA-7c3j-f7w2-p8f6'
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-03-25T03:56:13.406265Z'
scores:
  nvd: 9.8
  cna: 9.5
epss: 0.01286
epssPercentile: 0.70272
ingestedAt: '2026-11-05T06:38:03.608Z'
---

## Overview

OpenWrt Project is a Linux operating system targeting embedded devices. In versions prior to 24.10.6 and 25.12.1, the mdns daemon has a Stack-based Buffer Overflow vulnerability in the parse_question function. The issue is  triggered by PTR queries for reverse DNS domains (.in-addr.arpa and .ip6.arpa). DNS packets received on UDP port 5353 are expanded by dn_expand into an 8096-byte global buffer (name_buffer), which is then copied via an unbounded strcpy into a fixed 256-byte stack buffer when handling TYPE_PTR queries. The overflow is possible because dn_expand converts non-printable ASCII bytes (e.g., 0x01) into multi-character octal representations (e.g., \001), significantly inflating the expanded name beyond the stack buffer's capacity. A crafted DNS packet can exploit this expansion behavior to overflow the stack buffer, making the vulnerability reachable through normal multicast DNS packet processing. This issue has been fixed in versions 24.10.6 and 25.12.1.

## Affected

- `openwrt < 24.10.6`
- `openwrt >= 25.12.0, < 25.12.1`

## Remediation

Upgrade past the affected range:

- `openwrt 25.12.1`