{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74270", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.879Z", "datePublished": "2026-08-15T05:57:44.195Z", "dateUpdated": "2026-08-17T05:45:16.772Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:45:16.772Z" }, "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": { "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" }, "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "Documentation/netlink/specs/handshake.yaml", "net/handshake/genl.c" ], "versions": [ { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "25fb53e43ec006ac69b9e825a7e8a11d63a6083e", "status": "affected", "versionType": "git" }, { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "b6557f912509abe8e70223373dd7a44d1d4a0d6c", "status": "affected", "versionType": "git" }, { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "67cec2f1eb9e58719d622e92e2278ceda72dbd85", "status": "affected", "versionType": "git" }, { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "4dafc411948469277b276724c3b2b4408c02c04c", "status": "affected", "versionType": "git" }, { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "81246a65303d9635266b1334490142caaf86a11f", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "Documentation/netlink/specs/handshake.yaml", "net/handshake/genl.c" ], "versions": [ { "version": "6.4", "status": "affected" }, { "version": "0", "lessThan": "6.4", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "6.4", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "7.2" } ] } ] } ], "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" } } } }