{
  "cveId": "CVE-2026-99033",
  "url": "https://patchblox.com/security/cve/CVE-2026-99033",
  "summary": "CVE-2026-99033 is fixed in 19 products on 1 platform, first by DEBIAN-CVE-2026-99033, released October 24, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "net/packet: guard the ll header push in packet_rcv_spkt()",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  net/packet: guard the ll header push in packet_rcv_spkt()  packet_rcv_spkt() restores the link layer header with  \tskb_push(skb, skb-\u003Edata - skb_mac_header(skb));  That subtraction is only meaningful when the device actually has a link layer header.  packet_rcv() and tpacket_rcv() both wrap it in dev_has_header(), which is also the predicate the block comment at the top of the file states the restore in terms of; packet_rcv_spkt() does not.  commit d549699048b4 (\u0022net/packet: fix packet receive on L3 devices without visible hard header\u0022) introduced the helper and changed the two call sites, and this one stayed behind.  A device without a visible ll header can leave skb-\u003Emac_header at the 0xFFFF sentinel that __alloc_skb() initialises it to.  A CAN skb does: init_can_skb() sets pkt_type and ip_summed but does not reset the headers, and commit 9f10374bb024 (\u0022can: remove private CAN skb headroom infrastructure\u0022) dropped the skb_reset_*_header() calls that used to be there.  skb_mac_header() is then 0xFFFF, the length becomes a large negative number and skb_push() reports it through skb_under_panic() -- from softirq context, so it is a full system panic even with panic_on_oops=0:    skbuff: skb_under_panic: text:ffffffff8bd21bc1 len:-65455 put:-65471 head:... data:... tail:0x50 end:0x180 dev:can0   kernel BUG at net/core/skbuff.c:214!   RIP: 0010:skb_panic\u002B0x50/0x60   Call Trace:    \u003CIRQ\u003E    skb_push\u002B0x38/0x40    packet_rcv_spkt\u002B0xe1/0x170    __netif_receive_skb_core.constprop.0\u002B0x7e8/0xd30    ...   Kernel panic - not syncing: Fatal exception in interrupt  The socket type is reachable: packet_create() accepts SOCK_PACKET alongside SOCK_RAW and SOCK_DGRAM behind the same CAP_NET_RAW check, and neither the socket length nor a capability check keeps it away from a CAN interface.  The missing skb_reset_*_header() calls in init_can_skb() are a regression in their own right and are being fixed separately, but a packet socket should not turn a link layer that did not initialise its mac header into a kernel panic.  Guard the push the way the other two receive paths do.  Tested on v7.3-rc5 under QEMU with a slcan device on a pty, which is the driver RX path: vcan does not reproduce it, because can_send() resets the headers on the way out.  One SOCK_PACKET socket bound to can0 and one frame written into the line discipline panics an unpatched kernel with the trace above; the same image with this patch prints no panic and powers off normally.  Both kernels are this tree, defconfig plus CONFIG_CAN_SLCAN=y, differing only in this hunk.",
  "published": "2026-10-23T13:17:26Z",
  "severity": "Moderate",
  "cvss": 4.4,
  "epss": 0.00185,
  "epssPercentile": 0.08155,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-99033",
  "fixes": [
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      "product": "bpftool6.12",
      "release": "amzn 2023",
      "fixedVersion": "1:6.12.113-138.209.amzn2023",
      "fix": "ALAS2023-2026-3335",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3335",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "product": "bpftool6.12-debuginfo",
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      "fix": "ALAS2023-2026-3335",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3335",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "product": "kernel-livepatch-6.12.113-138.209",
      "release": "amzn 2023",
      "fixedVersion": "1:1.0-0.amzn2023",
      "fix": "ALAS2023-2026-3335",
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      "released": "2026-11-07T01:06:52Z"
    },
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      "fix": "ALAS2023-2026-3335",
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      "released": "2026-11-07T01:06:52Z"
    },
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      "fix": "ALAS2023-2026-3335",
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      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "fix": "ALAS2023-2026-3335",
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      "released": "2026-11-07T01:06:52Z"
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      "fix": "ALAS2023-2026-3335",
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      "fix": "ALAS2023-2026-3335",
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      "fix": "ALAS2023-2026-3335",
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      "fix": "ALAS2023-2026-3335",
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      "released": "2026-11-07T01:06:52Z"
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    {
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      "fix": "DEBIAN-CVE-2026-99033",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-99033",
      "released": "2026-10-24T13:25:57Z"
    },
    {
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  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T19:12:23Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}