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TI-2026-44178 Aliases CVE-2026-61720

FluidSynth: SF2 DMOD Chunk Unsigned Underflow

Priority LOW 27CWE-191Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-191 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00184 8th percentileScored 2026-11-07
Fix Fixed fluidsynth (FluidSynth): 2.5.6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
FluidSynthfluidsynth2.5.0 to before 2.5.62.5.6Patch availableCNA
  • fluidsynth VendorFluidSynth Affected 2.5.0 to before 2.5.6 Fixed in 2.5.6 Patch available CNA

Remediation

  • Fix · CNA fluidsynth (FluidSynth) Fixed in 2.5.6

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-61720

References

Other 3

  • TI-2025-35279 fluidsynth-2.4.6 and earlier versions is vulnerable to Null pointer dereference in… CVSS 3.1HIGH 7.5
  • TI-2025-42135 Use after free in fluidsynth CVSS 3.1HIGH 7.0
  • TI-2026-74907 Out-of-bounds write in FluidSynth SoundFont modulator handling CVSS 4.0MEDIUM 6.9
  • TI-2026-41957 FluidSynth: Heap-based buffer overrun CVSS 3.1CRITICAL 9.8
  • TI-2026-44176 FluidSynth: Heap Buffer Overflow in MIDI Player CVSS 3.1HIGH 7.8
  • TI-2026-44179 FluidSynth: Heap-based buffer overrun for DLS samples CVSS 3.1HIGH 8.0
See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences