CVE-2023-43240: D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter sip_address in ipportFilter.

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 sip_address in ipportFilter.

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/ipportFilter

snort

alert http any any -> $HOME_NET any (msg:"ET WEB_SPECIFIC_APPS D-Link ipportFilter sip_address Parameter Buffer Overflow Attempt (CVE-2023-43240)"; flow:established,to_server; http.method; content:"POST"; http.uri; bsize:20; content:"/goform/ipportFilter"; fast_pattern; http.request_body; content:"sip_address|3d|"; pcre:"/^[^&]{100,}(?:&|$)/R"; reference:url,github.com/peris-navince/founded-0-days/blob/main/Dlink/816/ipportFilter/1.md; reference:cve,2023-43240; classtype:web-application-attack; sid:2065138; rev:1; metadata:affected_product D_Link, attack_target Networking_Equipment, tls_state plaintext, created_at 2025_10_10, cve CVE_2023_43240, 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

sip_address=

→Exploit targets HTTP POST requests to /goform/ipportFilter with a sip_address parameter value exceeding 100 characters (stack overflow trigger).
→Traffic is expected in plaintext (no TLS); deploy detection at the network perimeter and internally facing D-Link DIR-816 A2 devices.
→The URI match uses an exact byte-size constraint (bsize:20) on /goform/ipportFilter to reduce false positives.

·Vulnerable device is specifically D-Link DIR-816 A2 firmware version v1.10CNB05; detections should be scoped to that device/firmware to avoid noise. ↗
·The PCRE threshold of 100+ characters for sip_address is the overflow trigger; tuning this threshold may be needed to balance detection sensitivity vs. false positives.

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