{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "2.5.0"
              },
              {
                "fixed": "2.5.6"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "df432e151dcaf463b1ecc7e873803bfa19733fd3"
            },
            {
              "fixed": "096e1ff0d09ddcac83d94923440706f76f94bc44"
            },
            {
              "fixed": "e5b11058a619246cea42976dacb76ca54be3d45d"
            }
          ],
          "repo": "https://github.com/fluidsynth/fluidsynth",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-rmc4-c8hw-455w"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-191"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61720.json"
  },
  "details": "FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the SF2 parser computes the DMOD modulator count as chunk.size / SF_MOD_SIZE - 1 without rejecting chunks smaller than one record. A crafted SF2 file containing a zero-sized DMOD chunk makes the unsigned subtraction wrap to UINT_MAX, and the parser then attempts billions of SFMod allocations. This exhausts process memory and causes denial of service. No workaround is available. This issue is fixed in version 2.5.6.",
  "id": "CVE-2026-61720",
  "modified": "2026-09-20T11:30:36.185064527Z",
  "published": "2026-09-18T20:03:43.989Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61720.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-rmc4-c8hw-455w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-61720"
    },
    {
      "type": "FIX",
      "url": "https://github.com/FluidSynth/fluidsynth/commit/096e1ff0d09ddcac83d94923440706f76f94bc44"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "FluidSynth: SF2 DMOD Chunk Unsigned Underflow"
}