# CVE-2026-76870 — Netcore NR255-V

> As of 2026-09-15, CVE-2026-76870 is a HIGH-severity vulnerability in Netcore NR255-V, CVSS v3.1 7.1, EPSS 0.3% (24.2th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-76870 as of 2026-09-15; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-15

## What is CVE-2026-76870?

Netcore NR255-V version 1.5.130703 contains an out-of-bounds read vulnerability in the mtd_write pre-flash validation routine triggered by short firmware uploads. Attackers can upload a truncated firmware image via put_file_cgi.c to trigger out-of-bounds reads across main.c, check_image_uuid.c, and oemMD5Update.c.

The record classifies CVE-2026-76870 under weakness class [CWE-125](https://intel.threadlinqs.com/cwe/CWE-125). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 20 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.1 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H`)
- **CVSS v4.0 base score:** 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 24.2% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-15

## Is CVE-2026-76870 being exploited?

It currently carries a trending score of 36 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Netcore](https://intel.threadlinqs.com/vendors/netcore): NR255-V

## How to fix CVE-2026-76870

No vendor patch reference has been recorded for CVE-2026-76870 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-76870

No threat campaign in the Threadlinqs corpus currently references CVE-2026-76870, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-09-16.

**Third-party advisory**

- [github.com — third party advisory](https://github.com/draw-ctf/netcore-router-public-refs/blob/main/2026.08.19-netcore-nr255v-firmware-upload-oob.md)
- [vulncheck.com — third party advisory](https://www.vulncheck.com/advisories/netcore-nr255-v-1.5.130703-out-of-bounds-read-in-mtd-write-firmware-upload-validation)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-76870
Full detection coverage and IOCs for threats exploiting CVE-2026-76870 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp