Quick answers
- Is CVE-2026-61721 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-61721 being exploited in the wild.
- How severe is CVE-2026-61721?
- High severity, with a CVSS score of 8, published 18 September 2026.
- Which products and versions are affected?
- FluidSynth 2.5.0 to 2.5.5.
- Is there a fix for CVE-2026-61721?
- A patch was published on 2026-07-04: Fixed in version 2.5.6 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-61721 attacked?
- It is attacked over the network or with local access, in a software library.
- Am I affected by CVE-2026-61721?
- Check whether you run FluidSynth at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The native DLS file loader fails to validate sample loop start and loop length values from the wsmp chunk before use, allowing out-of-bounds read access during audio rendering. The vulnerability affects the fluid_dls.cpp parser when the CMake option enable-native-dls is set to ON (default). An attacker can craft a malicious DLS file that triggers heap buffer reads beyond allocated boundaries, potentially disclosing sensitive memory or causing denial of service.
Affected products
- FluidSynth FluidSynth 2.5.0 to 2.5.5
Timeline
- 2026-09-18: disclosed
- 2026-07-04: patched: Fixed in version 2.5.6