{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "817aa094842dfc3a6b98c9582d4a647827f66201"
            },
            {
              "fixed": "f76b79d6e42af20682495bccd22f72c7164b0018"
            },
            {
              "fixed": "a1dc246f98bb94233effa4fa3ec7bf84700bb7d1"
            },
            {
              "fixed": "83e1aa9f5f906c9b1f4949d0521f0f950a159d96"
            },
            {
              "fixed": "95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.3.0"
            },
            {
              "fixed": "6.12.109"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.50"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89720.json"
  },
  "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-\u003elen field\nbefore handing the signature payload to verify_pkcs7_signature(), but the\ncheck has the wrong sign:\n\n\tif (le32_to_cpu(signode-\u003elen) \u003e snod-\u003elen + 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-\u003elen - 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-\u003esbuf, which is vmalloc(c-\u003eleb_size).\nverify_pkcs7_signature() -\u003e pkcs7_parse_message() -\u003e 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-\u003elen is guaranteed to be \u003e= UBIFS_SIG_NODE_SZ by the node scanner\n(c-\u003eranges[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.",
  "id": "CVE-2026-89720",
  "modified": "2026-09-13T03:30:54.077913208Z",
  "published": "2026-09-11T19:46:32.923Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/83e1aa9f5f906c9b1f4949d0521f0f950a159d96"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a1dc246f98bb94233effa4fa3ec7bf84700bb7d1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f76b79d6e42af20682495bccd22f72c7164b0018"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89720.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89720"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "ubifs: fix out-of-bounds read in signature length check"
}