FluidSynth up to 2.5.5 Native DLS Parser integer overflow

Summaryinfo

A vulnerability, which was classified as problematic, has been found in FluidSynth up to 2.5.5. This issue affects some unknown processing of the component Native DLS Parser. The manipulation leads to integer overflow. This vulnerability is uniquely identified as CVE-2026-61722. Local access is required to approach this attack. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in FluidSynth up to 2.5.5. It has been rated as problematic. This issue affects an unknown functionality of the component Native DLS Parser. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is integrity, and availability. The summary by CVE is:

FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 2.5.0 until 2.5.6, the native DLS parser validates articulation chunks using the unsigned expression cbsize + connblocks * 12 without first ensuring that the multiplication and addition fit in 32 bits. A crafted DLS file can supply a large connblocks value that wraps the expression and bypasses the chunk-size check, after which the parser performs approximately one billion 12-byte iterations beyond the chunk boundary. The excessive processing and invalid reads can cause denial of service. Builds with the CMake option enable-native-dls set to OFF do not expose the parser. This issue is fixed in version 2.5.6.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-61722 since 07/10/2026. The exploitation is known to be easy. Attacking locally is a requirement. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 2.5.6 eliminates this vulnerability.

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Productinfo

Name

• FluidSynth

Version

• 2.5.0
• 2.5.1
• 2.5.2
• 2.5.3
• 2.5.4
• 2.5.5

Website

• Product: https://github.com/FluidSynth/fluidsynth/

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CPE 2.2info

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