{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-80634",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-80634"
  ],
  "published": "2026-08-28T06:50:33Z",
  "summary": "netfilter: flowtable: avoid num_encaps underflow on bridge VLAN untag",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: avoid num_encaps underflow on bridge VLAN untag\n\nThe DEV_PATH_BR_VLAN_UNTAG case post-decrements info->num_encaps\ninside WARN_ON_ONCE(). num_encaps is u8, so if it's already 0 the\ndecrement still happens and wraps it to 255. The break only leaves\nthe inner switch -- a later path entry can set info->indev back to\na real device, and we end up returning with num_encaps == 255.\n\nnft_dev_forward_path() then walks info.encap[] (size 2) up to\nnum_encaps, which means an OOB stack read and a bogus count copied\ninto the route descriptor.\n\nShould only happen on a malformed bridge path stack, hence the WARN,\nbut worth handling sanely. Move the decrement out of the WARN.\n\n[ While at this, remove the WARN_ON_ONCE since this can only happen\n  with a buggy bridge path stack --pablo ].",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": null,
            "compiled_filter": false
          }
        }
      }
    },
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:13",
        "name": "linux"
      },
      "versions": [
        "1:6.18.50-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-2712",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v6",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v7",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v8",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.50-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.18.50-1+rpt1": {
            "linux_commit": "cff533aec2fa601846766b32ff57204e0a61bed7",
            "upstream_version": "6.18.50",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": null
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-80634"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2f55fa28011c97d6495d5787808db10a8c2d690d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e052f920773b73be49eb4d8702a9f85de7464363"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-29T06:25:05Z"
  }
}