{
  "cveId": "CVE-2026-80634",
  "url": "https://patchblox.com/security/cve/CVE-2026-80634",
  "summary": "CVE-2026-80634 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-80634, released August 29, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "netfilter: flowtable: avoid num_encaps underflow on bridge VLAN untag",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  netfilter: flowtable: avoid num_encaps underflow on bridge VLAN untag  The DEV_PATH_BR_VLAN_UNTAG case post-decrements info-\u003Enum_encaps inside WARN_ON_ONCE(). num_encaps is u8, so if it\u0027s already 0 the decrement still happens and wraps it to 255. The break only leaves the inner switch -- a later path entry can set info-\u003Eindev back to a real device, and we end up returning with num_encaps == 255.  nft_dev_forward_path() then walks info.encap[] (size 2) up to num_encaps, which means an OOB stack read and a bogus count copied into the route descriptor.  Should only happen on a malformed bridge path stack, hence the WARN, but worth handling sanely. Move the decrement out of the WARN.  [ While at this, remove the WARN_ON_ONCE since this can only happen   with a buggy bridge path stack --pablo ].",
  "published": "2026-08-28T08:16:48Z",
  "severity": "Low",
  "cvss": 9.8,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.006,
  "epssPercentile": 0.48971,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-80634",
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.115-2",
      "fix": "DEBIAN-CVE-2026-80634",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-80634",
      "released": "2026-08-29T00:46:20Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.1.5-1",
      "fix": "DEBIAN-CVE-2026-80634",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-80634",
      "released": "2026-08-29T00:46:20Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}