{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98239", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.329Z", "datePublished": "2026-10-06T08:45:10.611Z", "dateUpdated": "2026-10-19T09:16:10.911Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:16:10.911Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lan743x: fix RX checksum use-after-free\n\nlan743x_rx_process_buffer() adds each non-first receive buffer to the\nhead skb's frag_list. On the last descriptor, lan743x_rx_trim_skb()\nlinearizes the head and frees the fragment skb metadata.\n\nThe checksum-success path then writes ip_summed through the local skb\npointer, which still points to the final fragment. This causes a\nuse-after-free write when a packet spans more than one receive buffer.\n\nSet ip_summed on the surviving head skb instead. Multi-buffer receive\ncan occur after a live MTU increase because existing ring entries keep\ntheir old buffer size until they are replenished.\n\nA KUnit test invoking lan743x_rx_process_buffer() with a two-buffer\npacket produced a one-byte KASAN use-after-free write before this change.\nThe same test passed after the change. The driver object also builds\nwith W=1. This was not tested on physical LAN743x hardware." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The UAF write runs in lan743x_rx_process_buffer() (NAPI RX) while it handles an ordinary received Ethernet/IP frame from a remote sender. The sender's frame must be larger than the pre-change buffer size so the chip spreads it across several ring descriptors, which a routed jumbo-MTU path can deliver.\nAC:H - Buffers are sized mtu+ETH_HLEN+FCS+2 and the MAC caps frames at mtu+18 (MAC_RX_FSE_), so multi-buffer frames only occur after an admin raises the MTU on a live interface, while stale ring entries remain, or through the chip's occasional extra-buffer quirk. The remote attacker cannot produce either condition.\nPR:N - The trigger is a received frame with a valid checksum handled in the NAPI poll path, lan743x_rx_napi_poll -> lan743x_rx_process_buffer. The sender needs no authentication or credentials on the host.\nUI:N - Once the ring holds stale smaller buffers, no user on the victim needs to do anything; sending the oversized frame triggers the stale write. The admin's MTU change is already counted in AC:H.\nS:U - The freed sk_buff and the corrupted slab memory are inside the kernel itself; no VM, IOMMU or sandbox boundary is crossed.\nC:H - After skb_linearize() in lan743x_rx_trim_skb() frees the frag_list skb, its skbuff_head_cache slot can be reused by another skb. The stale write then hits a live object the attacker can steer with packet timing, which counts as a use-after-free per the scoring guidance.\nI:H - skb->ip_summed = CHECKSUM_UNNECESSARY is written into a freed sk_buff. If the slot has been reallocated, this corrupts another live skb and can make the stack accept forged or corrupted packets without checking their checksums. It is heap memory corruption.\nA:H - Writing into a freed and possibly reused sk_buff from the RX softirq can corrupt slab state and oops or panic the kernel; KASAN flagged the write in the author's KUnit reproducer." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/microchip/lan743x_main.c" ], "versions": [ { "version": "cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a", "lessThan": "0e52886c4324c9897c2c62f92be3dc8316cee67e", "status": "affected", "versionType": "git" }, { "version": "cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a", "lessThan": "a58024835c704419bb46d2a34e5223f65605f958", "status": "affected", "versionType": "git" }, { "version": "cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a", "lessThan": "6fe5c3a2503983abb431d93faeadfc7f5e6a7e33", "status": "affected", "versionType": "git" }, { "version": "cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a", "lessThan": "5c216bfa9fb7b36804485e67975e9c98055b31ef", "status": "affected", "versionType": "git" }, { "version": "cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a", "lessThan": "161a403c8625e152de03d1da22bbf9cda6dc9f9f", "status": "affected", "versionType": "git" }, { "version": "cd6910501cfd9a3bdff2f5fc33c9f3cf165ca54a", "lessThan": "a9ce4053dc945c5372dedba5017ee675b30dc0c5", "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/ethernet/microchip/lan743x_main.c" ], "versions": [ { "version": "6.1", "status": "affected" }, { "version": "0", "lessThan": "6.1", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.54", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.8", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "6.1", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1", "versionEndExcluding": "6.12.112" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1", "versionEndExcluding": "6.18.54" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1", "versionEndExcluding": "7.2.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0e52886c4324c9897c2c62f92be3dc8316cee67e" }, { "url": "https://git.kernel.org/stable/c/a58024835c704419bb46d2a34e5223f65605f958" }, { "url": "https://git.kernel.org/stable/c/6fe5c3a2503983abb431d93faeadfc7f5e6a7e33" }, { "url": "https://git.kernel.org/stable/c/5c216bfa9fb7b36804485e67975e9c98055b31ef" }, { "url": "https://git.kernel.org/stable/c/161a403c8625e152de03d1da22bbf9cda6dc9f9f" }, { "url": "https://git.kernel.org/stable/c/a9ce4053dc945c5372dedba5017ee675b30dc0c5" } ], "title": "net: lan743x: fix RX checksum use-after-free", "x_generator": { "engine": "bippy-1.2.0" } } } }