{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-52940", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-06-09T07:44:35.370Z", "datePublished": "2026-06-24T07:14:29.281Z", "dateUpdated": "2026-06-24T07:14:29.281Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-06-24T07:14:29.281Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntun: zero the whole vnet header in tun_put_user()\n\ntun_put_user() declares an on-stack struct virtio_net_hdr_v1_hash_tunnel\nwithout zeroing it. For a non-tunnel skb, virtio_net_hdr_tnl_from_skb()\nonly initializes the first 10 bytes (sizeof(struct virtio_net_hdr)),\nleaving bytes 10..23 (num_buffers and the hash/tunnel fields) as stack\ngarbage.\n\nAn unprivileged user can set the vnet header size to 24 with\nTUNSETVNETHDRSZ, so __tun_vnet_hdr_put() copies all 24 bytes of the\npartially-initialized struct to userspace, leaking 14 bytes of kernel\nstack on every read of a non-tunnel packet.\n\nFix it the same way tun_get_user() already does by zeroing the whole\nheader right after declaration."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/net/tun.c"], "versions": [{"version": "288f30435132d2f9e7a29ec9b9745a4f9dc7fd37", "lessThan": "5fd1fa5a4254bfdd70571c77f5e3bcb4e43738d5", "status": "affected", "versionType": "git"}, {"version": "288f30435132d2f9e7a29ec9b9745a4f9dc7fd37", "lessThan": "585cb85e9a29185be05f326369573c2663cf4380", "status": "affected", "versionType": "git"}, {"version": "288f30435132d2f9e7a29ec9b9745a4f9dc7fd37", "lessThan": "7f2fcff15e99bb852f6967396ed12b38376e2c8d", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/net/tun.c"], "versions": [{"version": "6.17", "status": "affected"}, {"version": "0", "lessThan": "6.17", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.36", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0.13", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1", "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": "6.17", "versionEndExcluding": "6.18.36"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.17", "versionEndExcluding": "7.0.13"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.17", "versionEndExcluding": "7.1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/5fd1fa5a4254bfdd70571c77f5e3bcb4e43738d5"}, {"url": "https://git.kernel.org/stable/c/585cb85e9a29185be05f326369573c2663cf4380"}, {"url": "https://git.kernel.org/stable/c/7f2fcff15e99bb852f6967396ed12b38376e2c8d"}], "title": "tun: zero the whole vnet header in tun_put_user()", "x_generator": {"engine": "bippy-1.2.0"}}}}

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