FluidSynth up to 2.5.5 Native DLS Parser poolcues.resize allocation of resources

Summaryinfo

A vulnerability has been found in FluidSynth up to 2.5.5 and classified as critical. The affected element is the function poolcues.resize of the component Native DLS Parser. This manipulation causes allocation of resources. The identification of this vulnerability is CVE-2026-61723. It is possible to initiate the attack remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical was found in FluidSynth up to 2.5.5. Affected by this vulnerability is the function poolcues.resize of the component Native DLS Parser. The manipulation with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. As an impact it is known to affect confidentiality, 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 ptbl chunks with the unsigned expression cues * 4 + cbsize without checking whether the multiplication and addition fit in 32 bits. A crafted DLS file can supply a large cues value that wraps the expression and passes the chunk-size check, causing poolcues.resize(cues) to request approximately four gigabytes and the parser to read billions of entries beyond the chunk boundary. The excessive allocation and invalid reads can cause denial of service. Builds with enable-native-dls set to OFF are not exposed. This issue is fixed in version 2.5.6.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-61723 since 07/10/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

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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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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