{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63830", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.014Z", "datePublished": "2026-07-19T12:02:23.741Z", "dateUpdated": "2026-08-17T04:51:39.075Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:51:39.075Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skmsg: preserve sg.copy across SG transforms\n\nThe sk_msg sg.copy bitmap is part of the scatterlist entry ownership\nstate. A set bit tells sk_msg_compute_data_pointers() not to expose the\nentry through writable BPF ctx->data. This protects entries backed by\npages that are not private to the sk_msg, such as splice-backed file\npage-cache pages.\n\nSeveral sk_msg transform paths move, copy, split, or compact\nmsg->sg.data[] entries without moving the matching sg.copy bit. This can\nmake an externally backed entry arrive at a new slot with a clear copy\nbit. A later SK_MSG verdict can then expose sg_virt(sge) as writable\nctx->data and BPF stores can modify the original page cache.\n\nKeep sg.copy synchronized with sg.data[] whenever entries are\ntransferred, shifted, split, or copied into a new sk_msg. Clear the bit\nwhen an entry is replaced by a newly allocated private page or freed.\nThis covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(),\nsk_msg_xfer(), and tls_split_open_record(), including the partial tail\nentry created during TLS open-record splitting." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L", "baseScore": 9.4, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The bug is exercised on the kTLS/TCP send path when splice-backed page-cache pages in an sk_msg are processed by an SK_MSG BPF verdict on network sockets; a remote TLS peer can trigger this on internet-facing servers (HTTPS, service-mesh edge nodes) that serve file-backed responses via splice/sendfile.\nAC:L - The attacker controls the traffic patterns, message sizes, and splice-backed data needed to hit the desynchronized transform paths (bpf_msg_push/pop/pull, sk_msg shift/xfer, tls_split_open_record); no race against unrelated system state is required.\nPR:N - On production kTLS servers with an attached SK_MSG BPF program (common in Cilium/Cloudflare-class deployments), an unauthenticated remote peer can trigger the faulty transforms without any credentials on the victim; a fully local exploit via user-namespace CAP_NET_ADMIN is also possible but is not the highest-severity case.\nUI:N - Exploitation requires only network traffic to a vulnerable server (or local socket I/O); no victim user action such as opening a file or mounting a filesystem is needed beyond normal server operation.\nS:U - Impact remains within the kernel's security authority (page-cache corruption via the network/BPF stack); it does not cross a VM-hypervisor or IOMMU boundary even though corrupted cache pages may affect other processes.\nC:H - Exposing splice-backed page-cache pages as writable BPF ctx->data gives the attacker a kernel memory write primitive over shared file cache pages, which can be leveraged to read or infer sensitive file contents served from or mapped through the corrupted pages.\nI:H - The commit explicitly states BPF stores through the incorrectly writable ctx->data can modify the original page cache, constituting arbitrary integrity corruption of file-backed data beyond the socket buffer.\nA:L - While the primary impact is data corruption rather than a kernel oops, corrupting shared page-cache pages of files actively served to other clients can cause sustained service disruption and repeated application-level failures; when uncertain, availability impact above None is appropriate." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/linux/skmsg.h", "net/core/filter.c", "net/core/skmsg.c", "net/tls/tls_sw.c" ], "versions": [ { "version": "d3b18ad31f93d0b6bae105c679018a1ba7daa9ca", "lessThan": "f126eed589eec6f201405abbc398844042ef6d57", "status": "affected", "versionType": "git" }, { "version": "d3b18ad31f93d0b6bae105c679018a1ba7daa9ca", "lessThan": "31a110642b5fb5e61940cbcfb503445ac4f28017", "status": "affected", "versionType": "git" }, { "version": "d3b18ad31f93d0b6bae105c679018a1ba7daa9ca", "lessThan": "9bb86d8184b37503816150c4a6ad3c17dfdbe827", "status": "affected", "versionType": "git" }, { "version": "d3b18ad31f93d0b6bae105c679018a1ba7daa9ca", "lessThan": "0eb4c16c4adb262763bda870a8ed38a1a9dec7ec", "status": "affected", "versionType": "git" }, { "version": "d3b18ad31f93d0b6bae105c679018a1ba7daa9ca", "lessThan": "d22cc92bc41290e5783a72375e0843d9435f6001", "status": "affected", "versionType": "git" }, { "version": "d3b18ad31f93d0b6bae105c679018a1ba7daa9ca", "lessThan": "1acdd14c0990dd1cd4b6534f00366d2e6dfce05f", "status": "affected", "versionType": "git" }, { "version": "d3b18ad31f93d0b6bae105c679018a1ba7daa9ca", "lessThan": "21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d", "status": "affected", "versionType": "git" }, { "version": "d3b18ad31f93d0b6bae105c679018a1ba7daa9ca", "lessThan": "406e8a651a7b854c41fecd5117bb282b3a6c2c6b", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/linux/skmsg.h", "net/core/filter.c", "net/core/skmsg.c", "net/tls/tls_sw.c" ], "versions": [ { "version": "4.20", "status": "affected" }, { "version": "0", "lessThan": "4.20", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.261", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.177", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.144", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.95", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.38", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.3", "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": "4.20", "versionEndExcluding": "5.10.261" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.1.177" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.6.144" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.12.95" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.18.38" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "7.1.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f126eed589eec6f201405abbc398844042ef6d57" }, { "url": "https://git.kernel.org/stable/c/31a110642b5fb5e61940cbcfb503445ac4f28017" }, { "url": "https://git.kernel.org/stable/c/9bb86d8184b37503816150c4a6ad3c17dfdbe827" }, { "url": "https://git.kernel.org/stable/c/0eb4c16c4adb262763bda870a8ed38a1a9dec7ec" }, { "url": "https://git.kernel.org/stable/c/d22cc92bc41290e5783a72375e0843d9435f6001" }, { "url": "https://git.kernel.org/stable/c/1acdd14c0990dd1cd4b6534f00366d2e6dfce05f" }, { "url": "https://git.kernel.org/stable/c/21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d" }, { "url": "https://git.kernel.org/stable/c/406e8a651a7b854c41fecd5117bb282b3a6c2c6b" } ], "title": "net: skmsg: preserve sg.copy across SG transforms", "x_generator": { "engine": "bippy-1.2.0" } } } }