{"item": {"cve_id": "CVE-2021-27137", "ghsa_id": "", "osv_id": "", "title": "CVE-2021-27137", "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).", "published_at": "2026-07-16T18:16:39.113", "modified_at": "2026-07-22T05:17:07.330", "vendor": "Dd-wrt", "product": "Dd-wrt", "affected_versions": ["0"], "fixed_versions": [], "cvss_score": 8.1, "cvss_version": "3.1", "cvss_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "severity": "HIGH", "epss_score": 0.03995, "epss_percentile": 0.90379, "epss_date": "2026-10-15", "is_kev": true, "kev_date": "2026-07-21", "kev_due_date": "2026-07-24", "kev_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.", "cwe_ids": ["CWE-121"], "attack_vector": "NETWORK", "attack_complexity": "HIGH", "privileges_required": "NONE", "user_interaction": "NONE", "references": ["https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html", "https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/", "https://svn.dd-wrt.com/changeset/45724", "https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/", "https://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmo", "https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/", "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137"], "source_urls": {"NVD": "https://nvd.nist.gov/vuln/detail/CVE-2021-27137", "CVE.org": "https://www.cve.org/CVERecord?id=CVE-2021-27137", "CISA": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137", "FIRST EPSS": "https://api.first.org/data/v1/epss?cve=CVE-2021-27137"}, "patch_available": null, "workaround_available": null, "sources": ["NVD", "CVE.org", "CISA", "FIRST EPSS"], "reference_items": [{"url": "https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html", "tags": ["Exploit", "Third Party Advisory"], "source": "NVD", "name": ""}, {"url": "https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/", "tags": ["Exploit", "Third Party Advisory"], "source": "NVD", "name": ""}, {"url": "https://svn.dd-wrt.com/changeset/45724", "tags": ["Patch"], "source": "NVD", "name": ""}, {"url": "https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/", "tags": ["Exploit", "Third Party Advisory"], "source": "NVD", "name": ""}, {"url": "https://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmo", "tags": ["Exploit"], "source": "NVD", "name": ""}, {"url": "https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/", "tags": ["Exploit", "Third Party Advisory", "exploit"], "source": "NVD", "name": ""}, {"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137", "tags": ["US Government Resource", "government-resource"], "source": "NVD", "name": ""}], "cvss_v4_score": null, "cvss_v4_vector": "", "cvss_v4_severity": "", "nvd_status": "Analyzed", "cna": "mitre", "date_reserved": "2021-02-10T00:00:00.000Z", "ssvc": {"options": {"Exploitation": "active", "Automatable": "no", "Technical Impact": "total"}, "version": "2.0.3", "timestamp": "2026-07-21T00:00:00+00:00", "role": "CISA Coordinator"}, "affected_products": [{"vendor": "Dd-wrt", "product": "Dd-wrt", "ranges": ["avant 45724"], "first_unaffected": ["45724"], "source": "NVD"}], "kev_name": "DD-WRT Stack-Based Buffer Overflow Vulnerability", "kev_short_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.", "kev_ransomware": "Unknown", "kev_notes": "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", "kev_cwes": ["CWE-121"], "wordfence_id": "", "mentions_sources": [], "version_match": "unknown", "risk_score": 71, "risk_class": "Critique", "impact": {"confidentialite": "élevé", "integrite": "élevé", "disponibilite": "élevé", "summary": "Un attaquant exploitant cette vulnérabilité pourrait, selon les conditions décrites par les sources, exploitable à distance (réseau), sans authentification préalable, affecter la confidentialité des données, l'intégrité du système et la disponibilité du service.", "basis": "CVSS 3.1"}, "mechanism": "Débordement de tampon sur la pile d'exécution.", "mitigation": {"correction": {"available": true, "text": "Mettre à jour : selon les sources, ne sont plus concernées les versions à partir de Dd-wrt 45724."}, "mitigation": {"specific": "Aucune mesure de mitigation spécifique confirmée par les sources consultées. Consultez les références officielles pour d'éventuelles mesures détaillées.", "general": ["Maintenir le produit à jour et activer les mises à jour de sécurité.", "Restreindre l'exposition réseau du service au strict nécessaire.", "Appliquer le principe du moindre privilège.", "Surveiller les journaux et les alertes de sécurité."], "specific_links": []}, "containment": {"applicable": true, "actions": ["Action recommandée par la 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.", "Isoler ou restreindre l'accès au service concerné.", "Restreindre les flux réseau entrants/sortants liés au composant.", "Renforcer la surveillance des journaux et des accès.", "Désactiver temporairement le composant vulnérable si l'activité le permet."]}, "note": "Priorité aux consignes officielles de l'éditeur et des références. Vérifiez toujours l'avis de sécurité avant toute intervention en production.", "official_links": [{"url": "https://svn.dd-wrt.com/changeset/45724", "groupe": "correctif", "groupe_titre": "Correctifs et versions corrigées", "editeur": "", "domaine": "svn.dd-wrt.com"}]}, "plain": {"verdict": "now", "verdict_label": "Exploité par des attaquants · à traiter aujourd'hui", "verdict_css": "now", "verdict_rank": 0, "headline": "Faille de sécurité signalée dans Dd-wrt", "headline_is_derived": false, "action": "Mettre à jour vers Dd-wrt 45724 ou plus récent, version publiée comme non concernée.", "action_kind": "update", "concerned": [{"version": "Dd-wrt 45724 ou plus récent", "state": "safe", "state_label": "Non concerné", "todo": "Rien à faire. Gardez les mises à jour automatiques activées."}, {"version": "0", "state": "hit", "state_label": "Concerné", "todo": "Mettre à jour vers Dd-wrt 45724 ou plus récent, version publiée comme non concernée."}, {"version": "Je ne connais pas ma version", "state": "unknown", "state_label": "À vérifier", "todo": "La version s'affiche généralement dans le menu « À propos » ou « Aide » du logiciel."}], "steps": [{"title": "Sauvegarder avant d'intervenir", "detail": "Une copie récente des données et de la configuration. Si votre hébergeur propose une sauvegarde en un clic, c'est le moment.", "duration": "10 min", "priority": false}, {"title": "Mettre à jour vers Dd-wrt 45724 ou plus récent, version publiée comme non concernée", "detail": "C'est la correction officielle. Tant qu'elle n'est pas appliquée, les autres mesures ne sont que temporaires.", "duration": "15 à 45 min", "priority": true}, {"title": "En attendant : réduire l'exposition sur Internet", "detail": "La faille est exploitable à distance. Limiter l'accès au service depuis l'extérieur (pare-feu, filtrage d'adresses, VPN) réduit fortement le risque.", "duration": "30 min", "priority": false}, {"title": "Vérifier que vous n'avez pas déjà été touché", "detail": "Cette faille est activement exploitée. Contrôler les comptes créés récemment, les connexions inhabituelles et les fichiers modifiés depuis la date de publication.", "duration": "30 min", "priority": true}, {"title": "Confirmer que tout fonctionne encore", "detail": "Après correction : page d'accueil, connexion, et les deux ou trois fonctions dont vous vous servez tous les jours.", "duration": "10 min", "priority": false}], "exploited": true, "exploited_label": "Oui, des attaques réelles sont constatées", "fixed_label": "Dd-wrt 45724 (non concernée selon les sources)", "affected_label": "0"}, "severity_display": "Élevée", "cvss_is_legacy": false, "risk_score_computable": true, "identifier": "CVE-2021-27137", "severity_fr": "Élevée", "epss_pct": 4.0, "source_records": [{"source": "NVD", "label": "NVD, NIST", "date_label": "Publié dans la base", "date": "2026-07-16", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-27137"}, {"source": "CVE.org", "label": "CVE.org, programme CVE", "date_label": "Publié par l'organisme CNA", "date": "2026-07-16", "url": "https://www.cve.org/CVERecord?id=CVE-2021-27137"}, {"source": "CISA", "label": "CISA KEV", "date_label": "Ajout au catalogue", "date": "2026-07-21", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137"}, {"source": "FIRST EPSS", "label": "FIRST EPSS", "date_label": "Score daté du", "date": "2026-10-15", "url": "https://api.first.org/data/v1/epss?cve=CVE-2021-27137"}], "exploit_public": true, "reseau_sans_auth": true, "exposition": "À distance, sans compte et sans action d'un utilisateur", "owasp": []}, "presentation": {"en_bref": [{"question": "Est-elle attaquée ?", "ton": "alerte", "reponse": "Oui, attaques constatées", "source": "Catalogue CISA KEV"}, {"question": "Existe-t-il un correctif ?", "ton": "bon", "reponse": "Oui : 45724", "source": "Versions publiées comme non concernées"}, {"question": "Comment l'attaquer ?", "ton": "alerte", "reponse": "À distance, sans compte et sans action d'un utilisateur", "source": "Vecteur CVSS publié"}, {"question": "Risque d'exploitation", "ton": "vigilance", "reponse": "4,0 % sur 30 jours", "source": "Plus probable que 90 % des failles connues"}], "references": [{"cle": "correctif", "titre": "Correctifs et versions corrigées", "explication": "Les pages que les sources désignent comme correctif ou notes de version.", "items": [{"url": "https://svn.dd-wrt.com/changeset/45724", "domaine": "svn.dd-wrt.com", "editeur": "", "etiquettes": ["Correctif"], "nom": "", "lien": true, "casse": false}]}, {"cle": "avis_tiers", "titre": "Avis d'autorités et d'organismes tiers", "explication": "CERT, agences gouvernementales, bases de vulnérabilités, chercheurs.", "items": [{"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137", "domaine": "www.cisa.gov", "editeur": "CISA", "etiquettes": ["Ressource gouvernementale américaine", "Ressource gouvernementale"], "nom": "", "lien": true, "casse": false}]}, {"cle": "exploit", "titre": "Codes d'exploitation référencés", "explication": "Les sources signalent un code d'exploitation public. Par prudence, CyberAlert affiche le site qui l'héberge sans lien direct : l'information utile ici est son existence, qui rend la faille plus facile à attaquer.", "items": [{"url": "https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html", "domaine": "securityaffairs.com", "editeur": "", "etiquettes": ["Code d'exploitation", "Avis d'un tiers"], "nom": "", "lien": false, "casse": false}, {"url": "https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/", "domaine": "ssd-disclosure.com", "editeur": "", "etiquettes": ["Code d'exploitation", "Avis d'un tiers"], "nom": "", "lien": false, "casse": false}, {"url": "https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/", "domaine": "www.bleepingcomputer.com", "editeur": "", "etiquettes": ["Code d'exploitation", "Avis d'un tiers"], "nom": "", "lien": false, "casse": false}, {"url": "https://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmo", "domaine": "www.fortinet.com", "editeur": "", "etiquettes": ["Code d'exploitation"], "nom": "", "lien": false, "casse": false}]}], "liens_correction": [{"url": "https://svn.dd-wrt.com/changeset/45724", "domaine": "svn.dd-wrt.com", "editeur": "", "etiquettes": ["Correctif"], "nom": "", "lien": true, "casse": false, "groupe": "correctif", "groupe_titre": "Correctifs et versions corrigées"}], "nb_exploits": 4, "cvss": {"version": "3.1", "vecteur": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "metriques": [{"code": "AV", "nom": "Vecteur d'attaque", "valeur": "Réseau (à distance, y compris par Internet)", "brut": "N", "explication": "D'où l'attaquant doit agir."}, {"code": "AC", "nom": "Complexité de l'attaque", "valeur": "Élevée", "brut": "H", "explication": "Conditions hors du contrôle de l'attaquant."}, {"code": "PR", "nom": "Privilèges requis", "valeur": "Aucun (pas de compte)", "brut": "N", "explication": "Droits dont l'attaquant a besoin avant d'attaquer."}, {"code": "UI", "nom": "Interaction de l'utilisateur", "valeur": "Aucune", "brut": "N", "explication": "Une victime doit-elle cliquer ou ouvrir quelque chose ?"}, {"code": "S", "nom": "Portée", "valeur": "Inchangée", "brut": "U", "explication": "L'attaque peut-elle toucher d'autres composants que celui qui est vulnérable ?"}, {"code": "C", "nom": "Confidentialité", "valeur": "Élevé", "brut": "H", "explication": "Accès à des informations protégées."}, {"code": "I", "nom": "Intégrité", "valeur": "Élevé", "brut": "H", "explication": "Modification de données ou du système."}, {"code": "A", "nom": "Disponibilité", "valeur": "Élevé", "brut": "H", "explication": "Arrêt ou ralentissement du service."}], "calculateur": "https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "specification": "https://www.first.org/cvss/v3.1/specification-document"}, "cvss4": null, "cwe": [{"id": "CWE-121", "nom": "Stack-based Buffer Overflow", "url": "https://cwe.mitre.org/data/definitions/121.html"}], "owasp": [], "ssvc": {"lignes": [{"nom": "Exploitation", "valeur": "Exploitation active constatée", "brut": "active"}, {"nom": "Automatisable", "valeur": "Non : l'attaque ne peut pas être entièrement automatisée", "brut": "no"}, {"nom": "Impact technique", "valeur": "Total : contrôle complet du composant ou de ses informations", "brut": "total"}], "version": "2.0.3", "date": "2026-07-21", "role": "CISA Coordinator", "url": "https://www.cisa.gov/stakeholder-specific-vulnerability-categorization-ssvc"}, "chronologie": [{"date": "2021-02-10", "libelle": "Identifiant réservé", "qui": "Programme CVE"}, {"date": "2026-07-16", "libelle": "Publication de la vulnérabilité", "qui": "mitre"}, {"date": "2026-07-21", "libelle": "Ajout au catalogue des failles exploitées", "qui": "CISA"}, {"date": "2026-07-21", "libelle": "Décision SSVC publiée", "qui": "CISA"}, {"date": "2026-07-22", "libelle": "Dernière mise à jour de la fiche source", "qui": "Source"}, {"date": "2026-07-24", "libelle": "Échéance de correction fixée par la CISA", "qui": "CISA"}, {"date": "2026-10-15", "libelle": "Calcul du score EPSS affiché", "qui": "FIRST"}], "liens_officiels": [{"nom": "NVD (NIST)", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-27137", "description": "Fiche de référence : CVSS, CPE, références étiquetées."}, {"nom": "CVE.org", "url": "https://www.cve.org/CVERecord?id=CVE-2021-27137", "description": "Enregistrement officiel publié par l'organisme qui a attribué l'identifiant."}, {"nom": "CISA KEV", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137", "description": "Entrée du catalogue des failles activement exploitées."}, {"nom": "FIRST EPSS", "url": "https://api.first.org/data/v1/epss?cve=CVE-2021-27137", "description": "Score de probabilité d'exploitation du jour."}, {"nom": "OSV.dev", "url": "https://osv.dev/vulnerability/CVE-2021-27137", "description": "Paquets open source concernés et versions corrigées."}, {"nom": "GitHub Advisory Database", "url": "https://github.com/advisories?query=CVE-2021-27137", "description": "Avis de sécurité des dépendances logicielles."}], "produits": [{"vendor": "Dd-wrt", "product": "Dd-wrt", "ranges": ["avant 45724"], "first_unaffected": ["45724"], "source": "NVD"}], "notes_kev": ["https://svn.dd-wrt.com/changeset/45724", "https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk", "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"]}, "consulted_at": "2026-10-16T02:11:24.079256+00:00"}