{"id":"CVE-2026-61720","state":"PUBLISHED","title":"FluidSynth: SF2 DMOD Chunk Unsigned Underflow","description":"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.","publishedAt":"2026-09-18T20:03:43.989Z","updatedAt":"2026-09-21T16:27:25.573Z","severity":{"score":6.2,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["FluidSynth fluidsynth"],"affected":[{"vendor":"FluidSynth","product":"fluidsynth","versions":[{"version":">= 2.5.0, < 2.5.6","status":"affected"}]}],"references":["https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-rmc4-c8hw-455w","https://github.com/FluidSynth/fluidsynth/commit/096e1ff0d09ddcac83d94923440706f76f94bc44","https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6"],"weaknesses":["CWE-191"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/61xxx/CVE-2026-61720.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-61720","state":"PUBLISHED","datePublished":"2026-09-18T20:03:43.989Z","dateUpdated":"2026-09-21T16:27:25.573Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-10T18:51:13.920Z"},"containers":{"cna":{"title":"FluidSynth: SF2 DMOD Chunk Unsigned Underflow","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"FluidSynth","product":"fluidsynth","versions":[{"version":">= 2.5.0, < 2.5.6","status":"affected"}]}],"references":[{"url":"https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-rmc4-c8hw-455w","name":"https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-rmc4-c8hw-455w","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/FluidSynth/fluidsynth/commit/096e1ff0d09ddcac83d94923440706f76f94bc44","name":"https://github.com/FluidSynth/fluidsynth/commit/096e1ff0d09ddcac83d94923440706f76f94bc44","tags":["x_refsource_MISC"]},{"url":"https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6","name":"https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":6.2,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-191","lang":"en","description":"CWE-191: Integer Underflow (Wrap or Wraparound)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-18T20:03:43.989Z"},"source":{"advisory":"GHSA-rmc4-c8hw-455w","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-21T16:27:05.665077Z","id":"CVE-2026-61720","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-21T16:27:25.573Z"}}]}}}