TI-2026-75497 Aliases CVE-2026-111711 GHSA-5769-g37j-m8jq

Pre-auth stack overflow in Netcore NR256CN Boa web server

MEDIUM 49CWE-121Published 2026-10-16 · Updated 2026-10-16

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-121 and the CVSS impact.

Summary

Netcore NR256CN through 1.5.140116 contains a pre-authentication stack overflow in the Boa web server's user_ok() function. The function copies Basic-auth usernames with unbounded strcpy() calls into 64-byte stack buffers, a stack-based buffer overflow (CWE-121). An unauthenticated remote attacker can send a username longer than 63 bytes to a protected /router/*.cgi route to crash the main Boa process or potentially execute code.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00492 42nd percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Netcore	NR256CN	up to 1.5.140116	—	No fix listed	CNA

NR256CN VendorNetcore Affected up to 1.5.140116 Fixed in — No fix listed CNA

Remediation

The sources list no fixed version for Netcore NR256CN.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Timeline

2026-10-16 Threatist record created from CVE-2026-111711
2026-10-16 Alias added: GHSA-5769-g37j-m8jq
2026-10-18 CISA SSVC decision points changed

References

Advisory 1

https://github.com/lukadqq/netcore-router-public-refs/blob/a44d562736b41c944223297e9144d2ad7fa2aff1/2026.10.15-netcore-nr256cn-basic-auth-stack-overflow.md

TI-2026-71052 Improper authentication in Netcore NR268 CGI Execution CVSS 4.0CRITICAL 10.0
TI-2026-65286 Netcore NAP930 Network Tools CGI network_tools eval os command injection CVSS 4.0CRITICAL 10.0
TI-2026-65110 Netcore NR289-GE boa_temp process_request missing authentication CVSS 4.0CRITICAL 10.0
TI-2026-65109 Netcore NR289-GE CGI set_ntp_server_ip.cgi system os command injection CVSS 4.0CRITICAL 10.0
TI-2026-65108 Netcore NR289-GE Location Time location_time.cgi system os command injection CVSS 4.0CRITICAL 10.0
TI-2026-65105 Netcore NR289-GE CGI ap_ip.cgi system os command injection CVSS 4.0CRITICAL 10.0

See all 60 →

Sources

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