---
id: "CVE-2026-111711"
kind: "vulnerability"
aliases: ["CVE-2026-111711"]
title: "Netcore NR256CN through 1.5.140116 contains a pre-authentication stack overflow vulnerability in the Boa web\u2026"
severity: "critical"
cvss: 9.8
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "NR256CN", "fixed": [], "affected": "<= 1.5.140116", "ecosystem": "vendor"}]
ecosystems: []
tags: ["boa-web-server", "embedded", "infrastructure", "netcore", "nr256cn", "routers"]
not_affected_if: ["admin-interface-not-exposed"]
published_at: "2026-10-16T18:17:55+00:00"
first_seen_at: "2026-10-23T21:57:13+00:00"
updated_at: "2026-10-23T23:28:44+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111711", "first_seen_at": "2026-10-23T21:57:13+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T23:28:44+00:00"}]
---

# Netcore NR256CN through 1.5.140116 contains a pre-authentication stack overflow vulnerability in the Boa web…

Netcore NR256CN routers through firmware 1.5.140116 have a stack overflow in the Boa web server's Basic-auth check, where an overlong username is copied into a 64-byte buffer without a length limit. An unauthenticated attacker can crash the web server or potentially run code on the device.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:NR256CN affected <= 1.5.140116 fixed ?

## How to check

Log in to the router admin page and read the firmware version (System/Status page); NR256CN on 1.5.140116 or earlier is affected. Check whether the web admin (Boa, /router/*.cgi) is reachable from WAN or from untrusted LAN segments, e.g. scan your public IP on the admin port (80/8080).

## Fix

No fixed firmware published as of 2026-10-23 (unknown; check Netcore support for a build newer than 1.5.140116). Mitigation: disable WAN/remote administration, restrict admin interface to a trusted management host, replace the device if it must be internet-facing.

## Timeline

- 2026-10-23T21:57:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111711
- 2026-10-23T23:28:44+00:00 analyst — Read researcher (Nebusec) reference and VulnCheck advisory: affected NR256CN firmware <= 1.5.140116, no vendor advisory or fixed version found anywhere; PoC withheld, no exploitation known, not in KEV. No X search done (obscure device, CVE-id-only coverage from aggregators).

## Documents

- [advisory] Nebusec: NR256CN Basic-auth stack overflow in user_ok (researcher reference) https://github.com/lukadqq/netcore-router-public-refs/blob/a44d562736b41c944223297e9144d2ad7fa2aff1/2026.10.15-netcore-nr256cn-basic-auth-stack-overflow.md
- [advisory] VulnCheck advisory: Netcore NR256CN pre-auth stack overflow https://www.vulncheck.com/advisories/netcore-nr256cn-through-1.5.140116-pre-auth-stack-overflow-via-boa-user-ok

## From the sources

Netcore NR256CN through 1.5.140116 contains a pre-authentication stack overflow vulnerability in the Boa web server's user_ok() function, which copies Basic-auth usernames with unbounded strcpy() calls into 64-byte stack buffers. Unauthenticated attackers can send a username longer than 63 bytes to any protected /router/*.cgi route to crash the main Boa process or potentially execute code.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_