CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Called exploited 43 days before disclosure.
Measured from the CVE publication date to the earliest of 3 KEV catalogues that list it.
The life of this vulnerability
- CVE published
- First KEV listing43d
- Last KEV listing48d
- Last sighting17d
Gaps are compressed to equal steps. The elapsed time is printed under each.
Which catalogues call it exploited
- CISA KEVUS federallisted Jul 21, 2026
- EUVDENISA, European Unionlisted Jul 21, 2026
- VulnCheck KEVcommercial researchlisted Jun 3, 2026
- CIRCLaggregator, mirrors the abovelisted Jul 21, 2026, not counted
3 catalogues list it. CIRCL aggregates the others and is shown but not counted.
Public exploitation evidence
- reported exploitationwww.recordedfuture.com/blog/july-2026-cve-landscape
- reported exploitationprevidian.com/CVE-2021-27137
- reported exploitationwww.cisa.gov/sites/default/files/feeds/known_exploited_vulne
- reported exploitationwww.recordedfuture.com/blog/june-2026-cve-landscape
- reported exploitationwww.fortinet.com/blog/threat-research/inside-cross-platform-
5 public reports collected from VulnCheck and CIRCL, first on Jun 3, 2026. Each links to its original source. We have not verified them.
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).
Required action (CISA)
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
