CVE-2021-27137: 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 re
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
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).
CSIRTS triage
- What
- An unsafe strcpy in DD-WRT allows an unauthenticated remote attacker to overflow an internal buffer.
- Who is affected
- All installations of DD-WRT before version 45724 are affected.
- Urgency
- Remediation is important due to the potential for exploitation.
- Action
- Update DD-WRT to version 45724 or later.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch DD-WRT
Get an email when a new DD-WRT advisory drops — max one per day, one-click unsubscribe.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2021-27137
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Exploitation confirmedCVE-2021-27137Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 97% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2021-27137 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- highexploitedCISA Adds Four Known Exploited Vulnerabilities to Catalogcisa
- criticalexploitedCVE-2021-27137: DD-WRT Stack-Based Buffer Overflow Vulnerabilitycisa-kev
More from NVD Recent CVEs
- mediumCVE-2026-67355: guzzlehttp/guzzle versions before 7.15.1 fail to preserve host-only cookie scope, storing the …2026-08-01
- mediumCVE-2026-67354: guzzlehttp/guzzle versions before 7.15.1 contain an information disclosure vulnerability in Re…2026-08-01
- mediumCVE-2026-67353: guzzlehttp/guzzle versions before 7.15.1 contain a denial of service vulnerability in the Cook…2026-08-01
- highCVE-2026-67352: luci-app-https-dns-proxy contains a stored cross-site scripting vulnerability in the resolver_…2026-08-01
- mediumCVE-2026-67344: ArcadeDB before 26.7.2 fails to enforce the UPDATE_SCHEMA database permission on the ALTER TYP…2026-08-01