{"api_version":"1","generated_at":"2026-08-18T06:24:48+00:00","cve":"CVE-2026-74270","urls":{"html":"https://cve.report/CVE-2026-74270","api":"https://cve.report/api/cve/CVE-2026-74270.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74270","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74270"},"summary":{"title":"handshake: Require admin permission for DONE command","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nhandshake: Require admin permission for DONE command\n\nACCEPT and DONE are the two downcalls of the handshake genl\nfamily, both intended for use by the trusted handshake agent\n(tlshd). ACCEPT already requires GENL_ADMIN_PERM; DONE has\nno privilege check at all.\n\nThe fd-lookup in handshake_nl_done_doit() only confirms that\nsome pending handshake request exists for the supplied sockfd;\nit does not authenticate the sender. An unprivileged process\nthat guesses or observes a valid sockfd can therefore submit\na DONE with HANDSHAKE_A_DONE_STATUS == 0, leaving the kernel\nconsumer to proceed as if the handshake succeeded. A non-zero\nstatus on a forged DONE tears down a legitimate in-flight\nhandshake before tlshd can report its real result.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:22:26","updated_at":"2026-08-17 06:19:20"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/4dafc411948469277b276724c3b2b4408c02c04c","name":"https://git.kernel.org/stable/c/4dafc411948469277b276724c3b2b4408c02c04c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/67cec2f1eb9e58719d622e92e2278ceda72dbd85","name":"https://git.kernel.org/stable/c/67cec2f1eb9e58719d622e92e2278ceda72dbd85","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b6557f912509abe8e70223373dd7a44d1d4a0d6c","name":"https://git.kernel.org/stable/c/b6557f912509abe8e70223373dd7a44d1d4a0d6c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/81246a65303d9635266b1334490142caaf86a11f","name":"https://git.kernel.org/stable/c/81246a65303d9635266b1334490142caaf86a11f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/25fb53e43ec006ac69b9e825a7e8a11d63a6083e","name":"https://git.kernel.org/stable/c/25fb53e43ec006ac69b9e825a7e8a11d63a6083e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74270","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74270","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae 25fb53e43ec006ac69b9e825a7e8a11d63a6083e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae b6557f912509abe8e70223373dd7a44d1d4a0d6c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae 67cec2f1eb9e58719d622e92e2278ceda72dbd85 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae 4dafc411948469277b276724c3b2b4408c02c04c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae 81246a65303d9635266b1334490142caaf86a11f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.4","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.145 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.97 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.40 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"74270","cve":"CVE-2026-74270","epss":"0.001280000","percentile":"0.029170000","score_date":"2026-08-17","updated_at":"2026-08-18 00:11:46"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["Documentation/netlink/specs/handshake.yaml","net/handshake/genl.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"25fb53e43ec006ac69b9e825a7e8a11d63a6083e","status":"affected","version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","versionType":"git"},{"lessThan":"b6557f912509abe8e70223373dd7a44d1d4a0d6c","status":"affected","version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","versionType":"git"},{"lessThan":"67cec2f1eb9e58719d622e92e2278ceda72dbd85","status":"affected","version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","versionType":"git"},{"lessThan":"4dafc411948469277b276724c3b2b4408c02c04c","status":"affected","version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","versionType":"git"},{"lessThan":"81246a65303d9635266b1334490142caaf86a11f","status":"affected","version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["Documentation/netlink/specs/handshake.yaml","net/handshake/genl.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.4"},{"lessThan":"6.4","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.145","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.97","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.40","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.145","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.97","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.40","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.5","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"6.4","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nhandshake: Require admin permission for DONE command\n\nACCEPT and DONE are the two downcalls of the handshake genl\nfamily, both intended for use by the trusted handshake agent\n(tlshd). ACCEPT already requires GENL_ADMIN_PERM; DONE has\nno privilege check at all.\n\nThe fd-lookup in handshake_nl_done_doit() only confirms that\nsome pending handshake request exists for the supplied sockfd;\nit does not authenticate the sender. An unprivileged process\nthat guesses or observes a valid sockfd can therefore submit\na DONE with HANDSHAKE_A_DONE_STATUS == 0, leaving the kernel\nconsumer to proceed as if the handshake succeeded. A non-zero\nstatus on a forged DONE tears down a legitimate in-flight\nhandshake before tlshd can report its real result."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - Exploitation requires sending a HANDSHAKE_CMD_DONE generic-netlink message via a local netlink socket to handshake_nl_done_doit(); although nfsd and nvmet-tcp are network-facing, the vulnerable control-plane downcall is not reachable from remote packets.\nAC:L - Once a process holds a sockfd for a socket with a pending handshake request, forging DONE with status 0 or a failure status is a single deterministic netlink operation; the commit describes sockfd guessing/observation as sufficient and no special timing beyond normal concurrency is required.\nPR:L - Before the fix, HANDSHAKE_CMD_DONE lacked GENL_ADMIN_PERM while ACCEPT required it, so any unprivileged local user with netlink access could invoke the handler without CAP_NET_ADMIN in the initial user namespace or any other elevated capability.\nUI:N - Exploitation does not require victim interaction such as opening files or mounting filesystems; the attacker sends a forged DONE netlink message directly to complete or abort an in-flight kernel handshake.\nS:U - Impact is confined to kernel TLS handshake state for local socket consumers (NFS RPC-over-TLS, NVMe-oF TCP TLS); it does not cross a VM, container, or IOMMU security boundary into a different authority.\nC:H - A forged DONE with HANDSHAKE_A_DONE_STATUS==0 makes kernel consumers proceed as if tlshd completed TLS successfully, bypassing X.509/PSK peer verification on NFS and NVMe-oF TCP sessions and undermining confidentiality of protected network storage traffic.\nI:H - The attacker can supply arbitrary HANDSHAKE_A_DONE_REMOTE_AUTH peer-identity values with a forged success, causing nfsd/nvmet to mark connections as TLS-authenticated and continue I/O under false security assumptions, corrupting integrity of access-control decisions.\nA:H - A forged DONE with non-zero status calls handshake_complete() with an error, tearing down legitimate in-flight handshakes before tlshd reports the real result and denying or disrupting TLS session establishment on NFS/NVMe-oF TCP services."}]}],"providerMetadata":{"dateUpdated":"2026-08-17T05:45:16.772Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/25fb53e43ec006ac69b9e825a7e8a11d63a6083e"},{"url":"https://git.kernel.org/stable/c/b6557f912509abe8e70223373dd7a44d1d4a0d6c"},{"url":"https://git.kernel.org/stable/c/67cec2f1eb9e58719d622e92e2278ceda72dbd85"},{"url":"https://git.kernel.org/stable/c/4dafc411948469277b276724c3b2b4408c02c04c"},{"url":"https://git.kernel.org/stable/c/81246a65303d9635266b1334490142caaf86a11f"}],"title":"handshake: Require admin permission for DONE command","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74270","datePublished":"2026-08-15T05:57:44.195Z","dateReserved":"2026-08-15T05:44:03.879Z","dateUpdated":"2026-08-17T05:45:16.772Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:22:26","lastModifiedDate":"2026-08-17 06:19:20","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74270","Ordinal":"1","Title":"handshake: Require admin permission for DONE command","CVE":"CVE-2026-74270","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74270","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nhandshake: Require admin permission for DONE command\n\nACCEPT and DONE are the two downcalls of the handshake genl\nfamily, both intended for use by the trusted handshake agent\n(tlshd). ACCEPT already requires GENL_ADMIN_PERM; DONE has\nno privilege check at all.\n\nThe fd-lookup in handshake_nl_done_doit() only confirms that\nsome pending handshake request exists for the supplied sockfd;\nit does not authenticate the sender. An unprivileged process\nthat guesses or observes a valid sockfd can therefore submit\na DONE with HANDSHAKE_A_DONE_STATUS == 0, leaving the kernel\nconsumer to proceed as if the handshake succeeded. A non-zero\nstatus on a forged DONE tears down a legitimate in-flight\nhandshake before tlshd can report its real result.","Type":"Description","Title":"handshake: Require admin permission for DONE command"}]}}}