CVE-2025-5623: D-Link DIR-816 · Stack-based Buffer Overflow
Affects D-Link DIR-816Source CVE Database V5
Not known to be exploited · 18% EPSS · CVSS 9.3 Critical · end of life, no fix coming : replace or isolate D-Link DIR-816; no fix will be released.
Data as of 26 Oct 2026, 11:42 UTC
- EPSS
- 18.5% chance of exploitation in 30 days – higher than 97% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- None coming – the product is end of life
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 5 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
No fix will be released: D-Link DIR-816 is end of life. Replace it, or isolate it from untrusted networks until you can.
AI-suggested
Given the lack of official patches, European organizations should prioritize the following mitigations: 1) Immediate inventory and identification of all D-Link DIR-816 routers running version 1.10CNB05 or similar legacy firmware. 2) Replace affected devices with currently supported and patched hardware models to eliminate the vulnerability. 3) If replacement is not immediately feasible, isolate the vulnerable routers from critical network segments and restrict access to the /goform/qosClassifier endpoint via firewall rules or network segmentation. 4) Monitor network traffic for unusual patterns indicative of exploitation attempts, such as unexpected requests to the qosClassifier endpoint or anomalous outbound connections. 5) Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics targeting this vulnerability or related exploit behaviors. 6) Educate IT staff and users about the risks of using unsupported network devices and the importance of timely hardware lifecycle management. 7) Regularly review and update network device inventories and security policies to prevent reliance on unsupported equipment.
Description
A vulnerability was found in D-Link DIR-816 1.10CNB05. It has been classified as critical. This affects the function qosClassifier of the file /goform/qosClassifier. The manipulation of the argument dip_address/sip_address leads to stack-based buffer overflow. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. This vulnerability only affects products that are no longer supported by the maintainer.