{"api_version":"1","generated_at":"2026-10-27T09:43:07+00:00","cve":"CVE-2026-98503","urls":{"html":"https://cve.report/CVE-2026-98503","api":"https://cve.report/api/cve/CVE-2026-98503.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98503","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98503"},"summary":{"title":"packet: use ubuf_info completion for TX_RING packets","description":"In the Linux kernel, the following vulnerability has been resolved:\n\npacket: use ubuf_info completion for TX_RING packets\n\ntpacket_snd sends skbs with frags pointing into its ring slots. Slots\nare released when skb->destructor is called.\n\nA call to skb_orphan calls skb->destructor before the skb is freed.\nThis can cause the slot to be reused while still linked into the skb.\n\nSwitch to standard zerocopy completion (ubuf_info) so the slot is only\nreleased once all references to the payload are freed or copied.\nRestore skb->destructor to standard sock_wfree.\n\nThe ubuf_info completion callback can be called with a NULL skb, but\nonly from net_zcopy_put and related API, used by zerocopy implementations\nthat hold their own reference on the uarg, such as MSG_ZEROCOPY. This\nuarg is only ever completed from skb_zcopy_clear, so skb is always set.\n\nTo prevent userspace from aliasing in-flight state on shared ring\nslots, allocate tpacket_uarg per packet, rather than per slot. This\nadds a small allocation to the transmit path. Use standard kmalloc to\nallow backporting to stable kernels.\n\nThe uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt\nreference. packet_free_tx_ring waits on sk_wmem_alloc before freeing\nthe ring pages. Always allocate vec->deferred for tx_ring so page-backed\nrings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs\nbefore calling tpacket_ubuf_complete.\n\nDrop the tx_ring.pg_vec test that tpacket_destruct_skb performed before\naccessing the slot. The sk_wmem_alloc reference now guarantees that the\nslot is valid. The test is also not sufficient by itself, as it reads\npg_vec without pg_vec_lock, so it can race with packet_set_ring.\n\nAs a result a slot is released when its payload is copied, which can\nbe before transmission (e.g., in skb_orphan_frags_rx). If copied\nbefore skb_tx_timestamp() is called, no slot timestamp is recorded,\nsimilar to when skb_orphan() was called early in the datapath before\nthis patch.\n\nRevert the now unused previous skb_zcopy_.._nouarg infra.\n\nDepends on commit 992cc9f94ca9 (\"net/packet: defer vmalloc TX_RING\nfree until skbs finish\").","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-18 16:17:01","updated_at":"2026-10-19 10:19:03"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/e67c455d79fbf709a94965f09a2be6bf4f4ba5fd","name":"https://git.kernel.org/stable/c/e67c455d79fbf709a94965f09a2be6bf4f4ba5fd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9518405613863d0bf0700927a21367f5942cf058","name":"https://git.kernel.org/stable/c/9518405613863d0bf0700927a21367f5942cf058","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/eda9bcb721f15a93746a99eabda33d80b86404fd","name":"https://git.kernel.org/stable/c/eda9bcb721f15a93746a99eabda33d80b86404fd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2a0c9afefc0ecea2cc30ccfbbbc98182a0986191","name":"https://git.kernel.org/stable/c/2a0c9afefc0ecea2cc30ccfbbbc98182a0986191","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98503","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98503","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 e67c455d79fbf709a94965f09a2be6bf4f4ba5fd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 eda9bcb721f15a93746a99eabda33d80b86404fd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 2a0c9afefc0ecea2cc30ccfbbbc98182a0986191 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5cd8d46ea1562be80063f53c7c6a5f40224de623 9518405613863d0bf0700927a21367f5942cf058 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 67f6fba765ef8cb19089d476e3c367212a2fbdfd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f2a67e68dbaeae7c88e5522873d7b908911f9f77 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.14.86 4.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.19.7 4.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.20","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.112 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.55 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.9 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/linux/skbuff.h","net/packet/af_packet.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"e67c455d79fbf709a94965f09a2be6bf4f4ba5fd","status":"affected","version":"5cd8d46ea1562be80063f53c7c6a5f40224de623","versionType":"git"},{"lessThan":"eda9bcb721f15a93746a99eabda33d80b86404fd","status":"affected","version":"5cd8d46ea1562be80063f53c7c6a5f40224de623","versionType":"git"},{"lessThan":"2a0c9afefc0ecea2cc30ccfbbbc98182a0986191","status":"affected","version":"5cd8d46ea1562be80063f53c7c6a5f40224de623","versionType":"git"},{"lessThan":"9518405613863d0bf0700927a21367f5942cf058","status":"affected","version":"5cd8d46ea1562be80063f53c7c6a5f40224de623","versionType":"git"},{"status":"affected","version":"67f6fba765ef8cb19089d476e3c367212a2fbdfd","versionType":"git"},{"status":"affected","version":"f2a67e68dbaeae7c88e5522873d7b908911f9f77","versionType":"git"},{"lessThan":"4.15","status":"affected","version":"4.14.86","versionType":"semver"},{"lessThan":"4.20","status":"affected","version":"4.19.7","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/linux/skbuff.h","net/packet/af_packet.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.20"},{"lessThan":"4.20","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.112","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.55","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.9","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.112","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.55","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.9","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.86","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.7","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\npacket: use ubuf_info completion for TX_RING packets\n\ntpacket_snd sends skbs with frags pointing into its ring slots. Slots\nare released when skb->destructor is called.\n\nA call to skb_orphan calls skb->destructor before the skb is freed.\nThis can cause the slot to be reused while still linked into the skb.\n\nSwitch to standard zerocopy completion (ubuf_info) so the slot is only\nreleased once all references to the payload are freed or copied.\nRestore skb->destructor to standard sock_wfree.\n\nThe ubuf_info completion callback can be called with a NULL skb, but\nonly from net_zcopy_put and related API, used by zerocopy implementations\nthat hold their own reference on the uarg, such as MSG_ZEROCOPY. This\nuarg is only ever completed from skb_zcopy_clear, so skb is always set.\n\nTo prevent userspace from aliasing in-flight state on shared ring\nslots, allocate tpacket_uarg per packet, rather than per slot. This\nadds a small allocation to the transmit path. Use standard kmalloc to\nallow backporting to stable kernels.\n\nThe uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt\nreference. packet_free_tx_ring waits on sk_wmem_alloc before freeing\nthe ring pages. Always allocate vec->deferred for tx_ring so page-backed\nrings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs\nbefore calling tpacket_ubuf_complete.\n\nDrop the tx_ring.pg_vec test that tpacket_destruct_skb performed before\naccessing the slot. The sk_wmem_alloc reference now guarantees that the\nslot is valid. The test is also not sufficient by itself, as it reads\npg_vec without pg_vec_lock, so it can race with packet_set_ring.\n\nAs a result a slot is released when its payload is copied, which can\nbe before transmission (e.g., in skb_orphan_frags_rx). If copied\nbefore skb_tx_timestamp() is called, no slot timestamp is recorded,\nsimilar to when skb_orphan() was called early in the datapath before\nthis patch.\n\nRevert the now unused previous skb_zcopy_.._nouarg infra.\n\nDepends on commit 992cc9f94ca9 (\"net/packet: defer vmalloc TX_RING\nfree until skbs finish\")."}],"providerMetadata":{"dateUpdated":"2026-10-19T09:20:42.115Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/e67c455d79fbf709a94965f09a2be6bf4f4ba5fd"},{"url":"https://git.kernel.org/stable/c/eda9bcb721f15a93746a99eabda33d80b86404fd"},{"url":"https://git.kernel.org/stable/c/2a0c9afefc0ecea2cc30ccfbbbc98182a0986191"},{"url":"https://git.kernel.org/stable/c/9518405613863d0bf0700927a21367f5942cf058"}],"title":"packet: use ubuf_info completion for TX_RING packets","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98503","datePublished":"2026-10-18T15:17:03.904Z","dateReserved":"2026-09-25T10:25:14.353Z","dateUpdated":"2026-10-19T09:20:42.115Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-18 16:17:01","lastModifiedDate":"2026-10-19 10:19:03","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98503","Ordinal":"1","Title":"packet: use ubuf_info completion for TX_RING packets","CVE":"CVE-2026-98503","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98503","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\npacket: use ubuf_info completion for TX_RING packets\n\ntpacket_snd sends skbs with frags pointing into its ring slots. Slots\nare released when skb->destructor is called.\n\nA call to skb_orphan calls skb->destructor before the skb is freed.\nThis can cause the slot to be reused while still linked into the skb.\n\nSwitch to standard zerocopy completion (ubuf_info) so the slot is only\nreleased once all references to the payload are freed or copied.\nRestore skb->destructor to standard sock_wfree.\n\nThe ubuf_info completion callback can be called with a NULL skb, but\nonly from net_zcopy_put and related API, used by zerocopy implementations\nthat hold their own reference on the uarg, such as MSG_ZEROCOPY. This\nuarg is only ever completed from skb_zcopy_clear, so skb is always set.\n\nTo prevent userspace from aliasing in-flight state on shared ring\nslots, allocate tpacket_uarg per packet, rather than per slot. This\nadds a small allocation to the transmit path. Use standard kmalloc to\nallow backporting to stable kernels.\n\nThe uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt\nreference. packet_free_tx_ring waits on sk_wmem_alloc before freeing\nthe ring pages. Always allocate vec->deferred for tx_ring so page-backed\nrings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs\nbefore calling tpacket_ubuf_complete.\n\nDrop the tx_ring.pg_vec test that tpacket_destruct_skb performed before\naccessing the slot. The sk_wmem_alloc reference now guarantees that the\nslot is valid. The test is also not sufficient by itself, as it reads\npg_vec without pg_vec_lock, so it can race with packet_set_ring.\n\nAs a result a slot is released when its payload is copied, which can\nbe before transmission (e.g., in skb_orphan_frags_rx). If copied\nbefore skb_tx_timestamp() is called, no slot timestamp is recorded,\nsimilar to when skb_orphan() was called early in the datapath before\nthis patch.\n\nRevert the now unused previous skb_zcopy_.._nouarg infra.\n\nDepends on commit 992cc9f94ca9 (\"net/packet: defer vmalloc TX_RING\nfree until skbs finish\").","Type":"Description","Title":"packet: use ubuf_info completion for TX_RING packets"}]}}}