CVE-2021-27137
8.1 · HIGH Actively ExploitedOverview
CVE-2021-27137 is a high-severity vulnerability affecting dd-wrt dd-wrt. It was published on July 16, 2026 and has a CVSS 3.1 base score of 8.1 (HIGH). This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
This vulnerability has a CVSS 3.1 base score of 8.1, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
An issue was discovered in router/upnp/src/ssdp.c in DD-WRT before 45724. An unsafe strcpy in the UPnP handling functionality allows an unauthenticated remote attacker to send a request that would overflow an internal fixed buffer. Exploitation requires the DD-WRT user to enable UPnP (which is off by default, and only listens on internal interfaces by default). This occurs in ssdp_msearch (reachable by an M-SEARCH request).
Remediation
Check the references section for vendor advisories and patches from dd-wrt. Update dd-wrt to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| dd-wrt | dd-wrt | >= 0, < 45724 | Affected |
References
Frequently Asked Questions
What is CVE-2021-27137?
CVE-2021-27137 is a high-severity vulnerability affecting dd-wrt dd-wrt. It was published on July 16, 2026 and has a CVSS 3.1 base score of 8.1 (HIGH). This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
How severe is CVE-2021-27137?
This vulnerability has a CVSS 3.1 base score of 8.1, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-27137?
Check the references section for vendor advisories and patches from dd-wrt. Update dd-wrt to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-27137?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-27137 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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Browser-based exploitation validates findings with real proof-of-concept.
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