Critical severity · published Oct 16, 2026
CVE-2026-111711
Netcore NR256CN through 1.5.140116 Pre-Auth Stack Overflow via Boa user_ok()
9.8
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 42% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NR
NR256CN · Netcore
through 1.5.140116 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-111711
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-111711
github.com
https://github.com/lukadqq/netcore-router-public-refs/blob/a44d562736b41c944223297e9144d2ad7fa2aff1/2026.10.15-netcore-nr256cn-basic-auth-stack-overflow.md
www.vulncheck.com
https://www.vulncheck.com/advisories/netcore-nr256cn-through-1.5.140116-pre-auth-stack-overflow-via-boa-user-ok
More from NR256CN
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CVE-2026-111710
Netcore NR256CN through 1.5.140116 Boa Web Server NULL Pointer Dereference DoS
6.5
CVE-2026-112016
Netcore NR256CN through 1.5.140116 Unauthenticated Write to Fixed Boa Staging Files
6.5
CVE-2026-111712
Netcore NR256CN through 1.5.140116 Authentication Bypass via CGI Path Prefix