{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-89720",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-89720"
  ],
  "published": "2026-09-11T19:47:07Z",
  "summary": "ubifs: fix out-of-bounds read in signature length check",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nubifs: fix out-of-bounds read in signature length check\n\nubifs_sb_verify_signature() bounds the on-disk ubifs_sig_node->len field\nbefore handing the signature payload to verify_pkcs7_signature(), but the\ncheck has the wrong sign:\n\n\tif (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node))\n\nThe signature bytes start sizeof(struct ubifs_sig_node) (UBIFS_SIG_NODE_SZ,\n64 bytes) into the node, so the payload is at most\n\n\tsnod->len - sizeof(struct ubifs_sig_node)\n\nbytes long. Adding the header size instead of subtracting it accepts a\ndeclared length up to 2 * UBIFS_SIG_NODE_SZ larger than the node actually\nholds -- past the end of c->sbuf, which is vmalloc(c->leb_size).\nverify_pkcs7_signature() -> pkcs7_parse_message() -> asn1_ber_decoder()\nis then handed that inflated length and reads beyond the allocation while\nwalking the DER headers. The node length comes straight from the mounted\nimage, so a crafted signed UBIFS image reaches this via\nubifs_read_superblock() before the signature is cryptographically checked.\n\nsnod->len is guaranteed to be >= UBIFS_SIG_NODE_SZ by the node scanner\n(c->ranges[UBIFS_SIG_NODE].min_len == UBIFS_SIG_NODE_SZ), so the corrected\nsubtraction cannot underflow. Legitimately signed images are unaffected: a\ncorrect superblock never declares a signature longer than the node it is\nembedded in.",
  "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": "6.1.188",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-89720"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ab7405bd86331cc2dbc8201699d4adc33bea75e7"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/11abc34698cb3172badf8aa12e623f1bac98bbd8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8cc3da72cf57acb4b77442ea8cec48425dff7c06"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/37a9d25a563f5f9103282954ce573c4a61321e7c"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f76b79d6e42af20682495bccd22f72c7164b0018"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a1dc246f98bb94233effa4fa3ec7bf84700bb7d1"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/83e1aa9f5f906c9b1f4949d0521f0f950a159d96"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-09-14T12:06:03Z"
  }
}