{"id":"CVE-2026-63830","state":"PUBLISHED","title":"net: skmsg: preserve sg.copy across SG transforms","description":"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.","publishedAt":"2026-07-19T12:02:23.741Z","updatedAt":"2026-10-19T20:07:49.188Z","severity":{"score":9.4,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"f126eed589eec6f201405abbc398844042ef6d57","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"31a110642b5fb5e61940cbcfb503445ac4f28017","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"9bb86d8184b37503816150c4a6ad3c17dfdbe827","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"0eb4c16c4adb262763bda870a8ed38a1a9dec7ec","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"d22cc92bc41290e5783a72375e0843d9435f6001","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"1acdd14c0990dd1cd4b6534f00366d2e6dfce05f","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"406e8a651a7b854c41fecd5117bb282b3a6c2c6b","versionType":"git"}],"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"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.20","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.20","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":"6.1.177","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.144","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/linux/skmsg.h","net/core/filter.c","net/core/skmsg.c","net/tls/tls_sw.c"]}],"references":["https://git.kernel.org/stable/c/f126eed589eec6f201405abbc398844042ef6d57","https://git.kernel.org/stable/c/31a110642b5fb5e61940cbcfb503445ac4f28017","https://git.kernel.org/stable/c/9bb86d8184b37503816150c4a6ad3c17dfdbe827","https://git.kernel.org/stable/c/0eb4c16c4adb262763bda870a8ed38a1a9dec7ec","https://git.kernel.org/stable/c/d22cc92bc41290e5783a72375e0843d9435f6001","https://git.kernel.org/stable/c/1acdd14c0990dd1cd4b6534f00366d2e6dfce05f","https://git.kernel.org/stable/c/21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d","https://git.kernel.org/stable/c/406e8a651a7b854c41fecd5117bb282b3a6c2c6b"],"weaknesses":["CWE-269"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63830.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63830","state":"PUBLISHED","datePublished":"2026-07-19T12:02:23.741Z","dateUpdated":"2026-10-19T20:07:49.188Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.014Z"},"containers":{"cna":{"title":"net: skmsg: preserve sg.copy across SG transforms","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"f126eed589eec6f201405abbc398844042ef6d57","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"31a110642b5fb5e61940cbcfb503445ac4f28017","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"9bb86d8184b37503816150c4a6ad3c17dfdbe827","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"0eb4c16c4adb262763bda870a8ed38a1a9dec7ec","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"d22cc92bc41290e5783a72375e0843d9435f6001","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"1acdd14c0990dd1cd4b6534f00366d2e6dfce05f","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d","versionType":"git"},{"version":"d3b18ad31f93d0b6bae105c679018a1ba7daa9ca","status":"affected","lessThan":"406e8a651a7b854c41fecd5117bb282b3a6c2c6b","versionType":"git"}],"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"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.20","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.20","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":"6.1.177","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.144","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/linux/skmsg.h","net/core/filter.c","net/core/skmsg.c","net/tls/tls_sw.c"]}],"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:51:39.075Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-63830","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:31:17.853447Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-269","lang":"en","type":"CWE","description":"CWE-269 Improper Privilege Management"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:07:49.188Z"}}]}}}