CVE-2026-76870: Out-of-bounds Read (CVSS 7.1)

Description

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.

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CVSS v3.1 Score

7.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H

EPSS — Exploit Prediction

0.0031

Probability of exploitation

0.24%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

References

Other References

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

Frequently Asked Questions

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. It has a CVSS v3.1 base score of 7.1 (HIGH).

How severe is CVE-2026-76870? +

CVE-2026-76870 has a CVSS v3.1 score of 7.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0031, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-76870? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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