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CVE-2021-27137 is a stack-based buffer overflow vulnerability in DD-WRT before build 45724. The flaw is located in router/upnp/src/ssdp.c within the UPnP handling logic, where an unsafe strcpy operation in the ssdp_msearch function copies attacker-controlled data into an internal fixed-size stack buffer without adequate bounds checking. The vulnerable code path is reachable through SSDP M-SEARCH requests. A remote unauthenticated attacker can send a specially crafted request that overflows the buffer when UPnP is enabled, potentially causing process instability or enabling arbitrary code execution on the affected router.
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No public exploit code observed for this vulnerability.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
45 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A DD-WRT vulnerability listed among vulnerabilities actively exploited or operationally weaponized in July 2026.
A stack-based buffer overflow vulnerability in DD-WRT firmware affecting routers and network appliances.
A stack-based buffer overflow vulnerability in DD-WRT mentioned as one of the flaws added to CISA's KEV catalog.
A stack-based buffer overflow vulnerability in DD-WRT UPnP handling that can allow unauthenticated remote code execution via a crafted M-SEARCH request when UPnP is enabled.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.