CVE Watch22 jul 2026

CVE-2021-27137

DD-WRT Stack-Based Buffer Overflow Vulnerability

CVSS

8.1

Alto

EPSS

4.0%

p90

KEV

SÍ

21 jul 2026

Exploit Today

0-100

Publicado: 16 jul 2026 · Última mod.: 22 jul 2026 · CWE-121

EPSS · 30d

4.0%EPSS · 30 días16.5%

2026-08-022026-08-31

Ficha del catálogo KEV

Producto

DD-WRT / DD-WRT

Vulnerabilidad

DD-WRT Stack-Based Buffer Overflow Vulnerability

Añadido a KEV

21 jul 2026

Remediar antes de

24 jul 2026

Uso conocido en ransomware

Descripción resumida

DD-WRT contains a stack-based buffer overflow vulnerability that could allow an unauthenticated attacker to overflow an internal buffer used by UPnP and trigger a code execution vulnerability.

Acción requerida

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.

Notas

This vulnerability affects a common open-source component, third-party library, proprietary implementation, or a protocol used by different products. Please check with specific vendors for information on patching status. For more information, please see: https://svn.dd-wrt.com/changeset/45724 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2021-27137

Descripción técnica

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).

Referencias oficiales

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