CVE-2026-30871

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The issue is triggered by PTR queries for reverse DNS domains (.in-addr.arpa and .ip6.arpa). DNS packets received on UDP port 5353 are expanded by dn_expand into an 8096-byte global buffer (name_buffer), which is then copied via an unbounded strcpy into a fixed 256-byte stack buffer when handling TYPE_PTR queries. The overflow is possible because dn_expand converts non-printable ASCII bytes (e.g., 0x01) into multi-character octal representations (e.g., \\001), significantly inflating the expanded name beyond the stack buffer's capacity. A crafted DNS packet can exploit this expansion behavior to overflow the stack buffer, making the vulnerability reachable through normal multicast DNS packet processing. This issue has been fixed in versions 24.10.6 and 25.12.1."}, {"lang": "es", "value": "El Proyecto OpenWrt es un sistema operativo Linux dirigido a dispositivos embebidos. En versiones anteriores a la 24.10.6 y 25.12.1, el demonio mdns tiene una vulnerabilidad de desbordamiento de b\u00fafer basado en pila en la funci\u00f3n parse_question. El problema se activa por consultas PTR para dominios DNS inversos (.in-addr.arpa y .ip6.arpa). Los paquetes DNS recibidos en el puerto UDP 5353 son expandidos por dn_expand en un b\u00fafer global de 8096 bytes (name_buffer), que luego se copia mediante un strcpy sin l\u00edmites en un b\u00fafer de pila fijo de 256 bytes al manejar consultas TYPE_PTR. El desbordamiento es posible porque dn_expand convierte bytes ASCII no imprimibles (p. ej., 0x01) en representaciones octales de m\u00faltiples caracteres (p. ej., \\001), inflando significativamente el nombre expandido m\u00e1s all\u00e1 de la capacidad del b\u00fafer de pila. Un paquete DNS manipulado puede explotar este comportamiento de expansi\u00f3n para desbordar el b\u00fafer de pila, haciendo que la vulnerabilidad sea alcanzable a trav\u00e9s del procesamiento normal de paquetes DNS multicast. Este problema ha sido corregido en las versiones 24.10.6 y 25.12.1."}], "id": "CVE-2026-30871", "lastModified": "2026-11-03T23:17:41.983", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "HIGH", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 9.5, "baseSeverity": "CRITICAL", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "HIGH", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "HIGH", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-30871", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-03-25T03:56:13.406265Z", "version": "2.0.3"}}]}, "published": "2026-03-19T22:16:31.633", "references": [{"source": "security-advisories@github.com", "tags": ["Release Notes"], "url": "https://github.com/openwrt/openwrt/releases/tag/v24.10.6"}, {"source": "security-advisories@github.com", "tags": ["Release Notes"], "url": "https://github.com/openwrt/openwrt/releases/tag/v25.12.1"}, {"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/openwrt/openwrt/security/advisories/GHSA-7c3j-f7w2-p8f6"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-121"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{"bugzilla": {"description": "OpenWrt: mdns: OpenWrt mdns daemon: Arbitrary code execution via crafted DNS packets", "id": "2449240", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2449240"}, "csaw": false, "cvss3": {"cvss3_base_score": "9.8", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-120", "details": ["A flaw was found in the OpenWrt mdns daemon. A remote attacker can exploit a Stack-based Buffer Overflow vulnerability in the `parse_question` function by sending specially crafted DNS (Domain Name System) packets. These packets, specifically PTR (Pointer Record) queries for reverse DNS domains, can cause the `dn_expand` function to inflate the size of the expanded name. This inflated name is then copied into a smaller fixed-size buffer using an unbounded copy operation, leading to a buffer overflow. This can result in arbitrary code execution or a denial of service (DoS) on the affected device."], "name": "CVE-2026-30871", "public_date": "2026-03-19T21:49:50Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-30871\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-30871\nhttps://github.com/openwrt/openwrt/releases/tag/v24.10.6\nhttps://github.com/openwrt/openwrt/releases/tag/v25.12.1\nhttps://github.com/openwrt/openwrt/security/advisories/GHSA-7c3j-f7w2-p8f6"], "threat_severity": "Critical"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,24.10.6)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[25.12.0-rc1,25.12.1)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "openwrt", "source": "cna", "vendor": "openwrt"}, "product": "openwrt", "vendor": "openwrt"}], "created": "2026-03-20T08:55:28.364576+00:00", "updated": "2026-06-18T10:15:03.037482+00:00", "vendors": ["openwrt", "openwrt$PRODUCT$openwrt"]}