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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 ov…

High CVSS 8.1
CVECVE-2021-27137
First seen2026-07-17 19:16 UTC
Disclosed2026-07-16 18:16 UTC
Last updated2026-07-17 19:16 UTC
Channel statusauto

Summary

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).

In-depth triage · Auto channel

No in-depth report has been generated yet (DR-003 v2 AI pipeline is under construction).

Lint boundary warnings (5)

The following non-blocking warnings were raised during the lint phase of this triage (e.g. reference URLs not yet on the allowlist). They do not affect entry usability and are disclosed for transparency (see DR-002).

  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html
  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/
  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://svn.dd-wrt.com/changeset/45724
  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/
  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/

Sources

  • NVD DATABASE

Original Links

Timeline

  1. nvd_ingest NVD