{"id":"CVE-2026-63829","state":"PUBLISHED","title":"net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ip_gre: require CAP_NET_ADMIN in the device netns for changelink\n\nA tunnel changelink() operates on at most two netns, dev_net(dev) and\nthe tunnel link netns t->net. They differ once the device is created in\nor moved to a netns other than the one the request runs in. The rtnl\nchangelink path checks CAP_NET_ADMIN only against dev_net(dev), so a\ncaller privileged there but not in t->net can rewrite a tunnel that\nlives in t->net.\n\nAdd rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in\nnet/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is\nskipped when the link netns is dev_net(dev), where the rtnl path already\nchecked it. The other patches in this series use the same helper.\n\nGate ipgre_changelink() and erspan_changelink() with it, at the top of\nthe op before any attribute is parsed, because the parsers update live\ntunnel fields first. ipgre_netlink_parms() sets t->collect_md before\nip_tunnel_changelink() runs.\n\nCommit 8b484efd5cb4 (\"ip6: vti: Use ip6_tnl.net in\nvti6_siocdevprivate().\") added the same check on the ioctl path. This\nadds it on RTM_NEWLINK.","publishedAt":"2026-07-19T12:02:23.191Z","updatedAt":"2026-10-19T20:07:49.035Z","severity":{"score":8.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"19275943d8fe903eb7b9aa53e380e41efd042ada","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"866b0f5ae599490bd496fd84581c68ac8b94e6af","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"92b766fc55156e0da2ecd0c2302c971118f8a229","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"e54c05ed3d9c28733fb9e5837219aca3691defa3","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"9831bc9ecb402957810c2045c663fbfe9b09e296","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"1697957eb0971d420dde42862b88eb43506a1105","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"47b5d3d506609b08b2e1f7c14f0b681a1953d572","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"8165f7ff57d9667d2bb477ef6af83ede7fed4ad7","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/rtnetlink.h","net/core/rtnetlink.c","net/ipv4/ip_gre.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.16","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/rtnetlink.h","net/core/rtnetlink.c","net/ipv4/ip_gre.c"]}],"references":["https://git.kernel.org/stable/c/19275943d8fe903eb7b9aa53e380e41efd042ada","https://git.kernel.org/stable/c/866b0f5ae599490bd496fd84581c68ac8b94e6af","https://git.kernel.org/stable/c/92b766fc55156e0da2ecd0c2302c971118f8a229","https://git.kernel.org/stable/c/e54c05ed3d9c28733fb9e5837219aca3691defa3","https://git.kernel.org/stable/c/9831bc9ecb402957810c2045c663fbfe9b09e296","https://git.kernel.org/stable/c/1697957eb0971d420dde42862b88eb43506a1105","https://git.kernel.org/stable/c/47b5d3d506609b08b2e1f7c14f0b681a1953d572","https://git.kernel.org/stable/c/8165f7ff57d9667d2bb477ef6af83ede7fed4ad7"],"weaknesses":["CWE-862"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63829.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63829","state":"PUBLISHED","datePublished":"2026-07-19T12:02:23.191Z","dateUpdated":"2026-10-19T20:07:49.035Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.014Z"},"containers":{"cna":{"title":"net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ip_gre: require CAP_NET_ADMIN in the device netns for changelink\n\nA tunnel changelink() operates on at most two netns, dev_net(dev) and\nthe tunnel link netns t->net. They differ once the device is created in\nor moved to a netns other than the one the request runs in. The rtnl\nchangelink path checks CAP_NET_ADMIN only against dev_net(dev), so a\ncaller privileged there but not in t->net can rewrite a tunnel that\nlives in t->net.\n\nAdd rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in\nnet/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is\nskipped when the link netns is dev_net(dev), where the rtnl path already\nchecked it. The other patches in this series use the same helper.\n\nGate ipgre_changelink() and erspan_changelink() with it, at the top of\nthe op before any attribute is parsed, because the parsers update live\ntunnel fields first. ipgre_netlink_parms() sets t->collect_md before\nip_tunnel_changelink() runs.\n\nCommit 8b484efd5cb4 (\"ip6: vti: Use ip6_tnl.net in\nvti6_siocdevprivate().\") added the same check on the ioctl path. This\nadds it on RTM_NEWLINK."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"19275943d8fe903eb7b9aa53e380e41efd042ada","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"866b0f5ae599490bd496fd84581c68ac8b94e6af","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"92b766fc55156e0da2ecd0c2302c971118f8a229","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"e54c05ed3d9c28733fb9e5837219aca3691defa3","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"9831bc9ecb402957810c2045c663fbfe9b09e296","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"1697957eb0971d420dde42862b88eb43506a1105","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"47b5d3d506609b08b2e1f7c14f0b681a1953d572","versionType":"git"},{"version":"b57708add31494175be741ed3fd24023b50c3423","status":"affected","lessThan":"8165f7ff57d9667d2bb477ef6af83ede7fed4ad7","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/rtnetlink.h","net/core/rtnetlink.c","net/ipv4/ip_gre.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.16","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/rtnetlink.h","net/core/rtnetlink.c","net/ipv4/ip_gre.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/19275943d8fe903eb7b9aa53e380e41efd042ada"},{"url":"https://git.kernel.org/stable/c/866b0f5ae599490bd496fd84581c68ac8b94e6af"},{"url":"https://git.kernel.org/stable/c/92b766fc55156e0da2ecd0c2302c971118f8a229"},{"url":"https://git.kernel.org/stable/c/e54c05ed3d9c28733fb9e5837219aca3691defa3"},{"url":"https://git.kernel.org/stable/c/9831bc9ecb402957810c2045c663fbfe9b09e296"},{"url":"https://git.kernel.org/stable/c/1697957eb0971d420dde42862b88eb43506a1105"},{"url":"https://git.kernel.org/stable/c/47b5d3d506609b08b2e1f7c14f0b681a1953d572"},{"url":"https://git.kernel.org/stable/c/8165f7ff57d9667d2bb477ef6af83ede7fed4ad7"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Exploitation requires sending RTM_NEWLINK changelink requests over rtnetlink (netlink socket), matching the kernel guidance that tc/netlink configuration paths are Local.\nAC:L - Once a cross-namespace GRE/ERSPAN device is present in the caller's netns, triggering the bug is a single deterministic netlink changelink with no races or attacker-uncontrollable timing.\nPR:L - The rtnl entry path requires CAP_NET_ADMIN in dev_net(dev), which an unprivileged user can obtain inside a user namespace via unshare --user --map-root-user --net without real init-namespace root.\nUI:N - Exploitation is fully programmatic through netlink; no victim user action such as opening a file or mounting a filesystem is required.\nS:C - The changelink mutates tunnel state in t->net while authorization is checked only against dev_net(dev), crossing from the attacker's net/user namespace into another tenant's or the host's network namespace tunnel tables.\nC:H - An attacker can rewrite IFLA_GRE_REMOTE/LOCAL, keys, and related tunnel parameters to redirect GRE/ERSPAN traffic through attacker-controlled endpoints and read tunneled payloads.\nI:H - Unauthorized changelink updates live tunnel fields (including collect_md and encap parameters parsed before the missing check), enabling arbitrary redirection or injection of traffic in the victim link netns.\nA:H - Rewriting tunnel endpoints, keys, or metadata handling can break production GRE/ERSPAN overlays and VPN paths, causing sustained loss of connectivity for dependent services."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:51:37.933Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"6.12.95"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"6.18.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"7.1.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-63829","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:31:15.242549Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-862","lang":"en","type":"CWE","description":"CWE-862 Missing Authorization"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:07:49.035Z"}}]}}}