Vulnerabilities CVE-2021-27137

CVE-2021-27137

High

Open

KEV

TLP:CLEAR

NVD CVE.org

AI Analysis

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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).

Details

CVSS Score: 8.1
EPSS Score ⓘ: 16.49%

96.7th percentile
CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Confidence: 100%
Published: Jul 16, 2026
Last Modified: Jul 16, 2026
CISA KEV
Date Added: Jul 21, 2026
Patch Due: Jul 24, 2026
Required Action: 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.

Notes

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