CVE-2023-43239: D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter flag_5G in showMACfilterMAC.

PriorityP266critical9.8CVSS 3.1

AVNACLPRNUINSUCHIHAH

EPSS

12.24%

95.7th percentile

D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter flag_5G in showMACfilterMAC.

Affected

1 ranges

Vendor	Product	Version range	Fixed in
dlink	dir-816_a2_firmware	—	—

Detection & IOCsextracted from sources · hover to see the quote

url/goform/showMACfilterMAC

snort

alert http any any -> $HOME_NET any (msg:"ET WEB_SPECIFIC_APPS D-Link showMACfilterMAC flag_5g Parameter Buffer Overflow Attempt (CVE-2023-43239)"; flow:established,to_server; http.method; content:"POST"; http.uri; bsize:24; content:"/goform/showMACfilterMAC"; fast_pattern; http.request_body; content:"flag_5g|3d|"; pcre:"/^[^&]{100,}(?:&|$)/R"; reference:url,github.com/peris-navince/founded-0-days/blob/main/Dlink/816/showMACfilterMAC/1.md; reference:cve,2023-43239; classtype:web-application-attack; sid:2065140; rev:1; metadata:affected_product D_Link, attack_target Networking_Equipment, tls_state plaintext, created_at 2025_10_10, cve CVE_2023_43239, deployment Perimeter, deployment Internal, performance_impact Low, confidence High, signature_severity Major, tag Exploit, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_10_10, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)

bytes

flag_5g=

→Exploit uses HTTP POST method targeting the URI /goform/showMACfilterMAC (exact URI length is 24 bytes); match on both method and URI for high-fidelity detection.
→The overflow is triggered via the flag_5g parameter in the POST body; a value exceeding ~100 characters (no ampersand delimiter) indicates exploitation attempt.
→Traffic is plaintext (not TLS); deploy detection at perimeter and internal network boundaries.
→MITRE mapping: Initial Access (TA0001) via Exploit Public-Facing Application (T1190); target is networking equipment (D-Link DIR-816 A2 v1.10CNB05).
→Reference PoC available at github.com/peris-navince/founded-0-days for further payload analysis.

·Affected device is specifically D-Link DIR-816 A2 firmware version v1.10CNB05; detections should be scoped to environments running this exact model/firmware. ↗

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