{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2025-21920", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.788Z", "datePublished": "2025-04-01T15:40:54.595Z", "dateUpdated": "2025-11-03T19:39:13.839Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2025-05-04T07:24:34.859Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvlan: enforce underlying device type\n\nCurrently, VLAN devices can be created on top of non-ethernet devices.\n\nBesides the fact that it doesn't make much sense, this also causes a\nbug which leaks the address of a kernel function to usermode.\n\nWhen creating a VLAN device, we initialize GARP (garp_init_applicant)\nand MRP (mrp_init_applicant) for the underlying device.\n\nAs part of the 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Adem\u00e1s del hecho de que no tiene mucho sentido, esto tambi\u00e9n causa un error que filtra la direcci\u00f3n de una funci\u00f3n del kernel al modo de usuario. Al crear un dispositivo VLAN, inicializamos GARP (garp_init_applicant) y MRP (mrp_init_applicant) para el dispositivo subyacente. Como parte del proceso de inicializaci\u00f3n, agregamos la direcci\u00f3n de multidifusi\u00f3n de cada solicitante al dispositivo subyacente, llamando a dev_mc_add. __dev_mc_add usa dev->addr_len para determinar la longitud de la nueva direcci\u00f3n de multidifusi\u00f3n. Esto causa una lectura fuera de los l\u00edmites si dev->addr_len es mayor que 6, ya que las direcciones de multidifusi\u00f3n proporcionadas por GARP y MRP solo tienen 6 bytes de longitud. Este comportamiento se puede reproducir utilizando los siguientes comandos: ip tunnel add gretest mode ip6gre local ::1 remote ::2 dev lo ip l set up dev gretest ip link add link gretest name vlantest type vlan id 100 Luego, el siguiente comando mostrar\u00e1 la direcci\u00f3n de garp_pdu_rcv: ip maddr show | grep 01:80:c2:00:00:21 Corrija el error aplicando el tipo de dispositivo subyacente durante la inicializaci\u00f3n del dispositivo VLAN."}], "id": "CVE-2025-21920", "lastModified": "2025-11-03T20:17:28.160", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.2, "source": "nvd@nist.gov", "type": "Primary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.2, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2025-04-01T16:15:22.673", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/0fb7aa04c19eac4417f360a9f7611a60637bdacc"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/30e8aee77899173a82ae5ed89f536c096f20aaeb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/3561442599804905c3defca241787cd4546e99a7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/5a515d13e15536e82c5c7c83eb6cf5bc4827fee5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/7f1564b2b2072b7aa1ac75350e9560a07c7a44fd"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/b33a534610067ade2bdaf2052900aaad99701353"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/b6c72479748b7ea09f53ed64b223cee6463dc278"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/fa40ebef69234e39ec2d26930d045f2fb9a8cb2b"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-125"}], "source": "nvd@nist.gov", "type": "Primary"}, {"description": [{"lang": "en", "value": "CWE-125"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"affected_release": [{"advisory": "RHSA-2025:8643", "cpe": "cpe:/a:redhat:enterprise_linux:9", "package": "kernel-0:5.14.0-570.21.1.el9_6", "product_name": "Red Hat Enterprise Linux 9", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:8643", "cpe": "cpe:/o:redhat:enterprise_linux:9", "package": "kernel-0:5.14.0-570.21.1.el9_6", "product_name": "Red Hat Enterprise Linux 9", "release_date": "2025-06-09T00:00:00Z"}], "bugzilla": {"description": "kernel: vlan: enforce underlying device type", "id": "2356639", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2356639"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.1", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "status": "verified"}, "cwe": "CWE-125", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nvlan: enforce underlying device type\nCurrently, VLAN devices can be created on top of non-ethernet devices.\nBesides the fact that it doesn't make much sense, this also causes a\nbug which leaks the address of a kernel function to usermode.\nWhen creating a VLAN device, we initialize GARP (garp_init_applicant)\nand MRP (mrp_init_applicant) for the underlying device.\nAs part of the initialization process, we add the multicast address of\neach applicant to the underlying device, by calling dev_mc_add.\n__dev_mc_add uses dev->addr_len to determine the length of the new\nmulticast address.\nThis causes an out-of-bounds read if dev->addr_len is greater than 6,\nsince the multicast addresses provided by GARP and MRP are only 6\nbytes long.\nThis behaviour can be reproduced using the following commands:\nip tunnel add gretest mode ip6gre local ::1 remote ::2 dev lo\nip l set up dev gretest\nip link add link gretest name vlantest type vlan id 100\nThen, the following command will display the address of garp_pdu_rcv:\nip maddr show | grep 01:80:c2:00:00:21\nFix the bug by enforcing the type of the underlying device during VLAN\ndevice initialization."], "name": "CVE-2025-21920", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-04-01T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-21920\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-21920\nhttps://lore.kernel.org/linux-cve-announce/2025040131-CVE-2025-21920-08ff@gregkh/T"], "threat_severity": "Moderate"}