KEV Entry

CVE-2021-27137

Known Exploited Vulnerability Entry CISA

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Entry Details
Confirmed Exploited

CVE-2021-27137

2026-07-21 00:00 UTC

Timestamps

2026-07-21

2026-07-21

Scope

DD-WRT Stack-Based Buffer Overflow Vulnerability | Affected: DD-WRT / DD-WRT | Description: 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. | 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. | Due date: 2026-07-24 | Known ransomware campaign use (KEV): Unknown | Notes (KEV): 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

References
  • {'id': 'CVE-2021-27137', 'url': 'https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-27137'}

1b340c4a-eaac-42b6-993b-564939a9e72a

CISA
405284c2-e461-4670-8979-7fd2c9755a60

2026-07-21 15:00 UTC

2026-07-21 15:00 UTC

Evidence
1
Type Source Signal Confidence Details GCVE Metadata
vendor_report cisa-kev successful_exploitation 0.80
View details 
{
  "cwes": [
    "CWE-121"
  ],
  "date_added": "2026-07-21",
  "due_date": "2026-07-24",
  "feed": "CISA Known Exploited Vulnerabilities Catalog",
  "knownRansomwareCampaignUse": "Unknown",
  "product": "DD-WRT",
  "vendorProject": "DD-WRT",
  "vulnerabilityName": "DD-WRT Stack-Based Buffer Overflow Vulnerability"
}
 -
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