{"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":"2026-05-11T21:09:05.513Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-05-11T21:09:05.513Z"},"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 initialization process, we add the multicast address of\neach applicant to the underlying device, by calling dev_mc_add.\n\n__dev_mc_add uses dev->addr_len to determine the length of the new\nmulticast address.\n\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.\n\nThis behaviour can be reproduced using the following commands:\n\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\n\nThen, the following command will display the address of garp_pdu_rcv:\n\nip maddr show | grep 01:80:c2:00:00:21\n\nFix the bug by enforcing the type of the underlying device during VLAN\ndevice initialization."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/8021q/vlan.c"],"versions":[{"version":"22bedad3ce112d5ca1eaf043d4990fa2ed698c87","lessThan":"7f1564b2b2072b7aa1ac75350e9560a07c7a44fd","status":"affected","versionType":"git"},{"version":"22bedad3ce112d5ca1eaf043d4990fa2ed698c87","lessThan":"fa40ebef69234e39ec2d26930d045f2fb9a8cb2b","status":"affected","versionType":"git"},{"version":"22bedad3ce112d5ca1eaf043d4990fa2ed698c87","lessThan":"0fb7aa04c19eac4417f360a9f7611a60637bdacc","status":"affected","versionType":"git"},{"version":"22bedad3ce112d5ca1eaf043d4990fa2ed698c87","lessThan":"5a515d13e15536e82c5c7c83eb6cf5bc4827fee5","status":"affected","versionType":"git"},{"version":"22bedad3ce112d5ca1eaf043d4990fa2ed698c87","lessThan":"3561442599804905c3defca241787cd4546e99a7","status":"affected","versionType":"git"},{"version":"22bedad3ce112d5ca1eaf043d4990fa2ed698c87","lessThan":"30e8aee77899173a82ae5ed89f536c096f20aaeb","status":"affected","versionType":"git"},{"version":"22bedad3ce112d5ca1eaf043d4990fa2ed698c87","lessThan":"b6c72479748b7ea09f53ed64b223cee6463dc278","status":"affected","versionType":"git"},{"version":"22bedad3ce112d5ca1eaf043d4990fa2ed698c87","lessThan":"b33a534610067ade2bdaf2052900aaad99701353","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/8021q/vlan.c"],"versions":[{"version":"2.6.35","status":"affected"},{"version":"0","lessThan":"2.6.35","status":"unaffected","versionType":"semver"},{"version":"5.4.291","lessThanOrEqual":"5.4.*","status":"unaffected","versionType":"semver"},{"version":"5.10.235","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.179","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.131","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.83","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.19","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.13.7","lessThanOrEqual":"6.13.*","status":"unaffected","versionType":"semver"},{"version":"6.14","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"5.4.291"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"5.10.235"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"5.15.179"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.1.131"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.6.83"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.12.19"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.13.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.14"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/7f1564b2b2072b7aa1ac75350e9560a07c7a44fd"},{"url":"https://git.kernel.org/stable/c/fa40ebef69234e39ec2d26930d045f2fb9a8cb2b"},{"url":"https://git.kernel.org/stable/c/0fb7aa04c19eac4417f360a9f7611a60637bdacc"},{"url":"https://git.kernel.org/stable/c/5a515d13e15536e82c5c7c83eb6cf5bc4827fee5"},{"url":"https://git.kernel.org/stable/c/3561442599804905c3defca241787cd4546e99a7"},{"url":"https://git.kernel.org/stable/c/30e8aee77899173a82ae5ed89f536c096f20aaeb"},{"url":"https://git.kernel.org/stable/c/b6c72479748b7ea09f53ed64b223cee6463dc278"},{"url":"https://git.kernel.org/stable/c/b33a534610067ade2bdaf2052900aaad99701353"}],"title":"vlan: enforce underlying device type","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.1,"attackVector":"LOCAL","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"LOW","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"id":"CVE-2025-21920","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2025-10-01T20:07:55.880454Z"}}}],"problemTypes":[{"descriptions":[{"lang":"en","type":"CWE","cweId":"CWE-125","description":"CWE-125 Out-of-bounds Read"}]}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2025-10-01T20:17:03.075Z"}},{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"},{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2025-11-03T19:39:13.839Z"}}]}}