CVE-2025-68617Public exploit

Crash or code execution via DLS unload race

Published Dec 23, 2025 · Updated Dec 24, 2025

Heap-based use-after-free in FluidSynth 2.5.0 through 2.5.1 allows context-dependent attackers to crash or execute code via DLS unloading. DLS deletion frees fonts still referenced by active samples, while synth teardown can delete loader-owned file callbacks before a timer thread uses them to close a lazily unloaded font. Native DLS support and concurrent unloading with active voices or synth destruction are required; the usual result is an application crash, with code execution possible in the embedding application's context.

CVSS severity7.0
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based use-after-free in FluidSynth 2.5.0 through 2.5.1 allows context-dependent attackers to crash or execute code via DLS unloading. DLS deletion frees fonts still referenced by active samples, while synth teardown can delete loader-owned file callbacks before a timer thread uses them to close a lazily unloaded font. Native DLS support and concurrent unloading with active voices or synth destruction are required; the usual result is an application crash, with code execution possible in the embedding application's context.

The record

CVE
CVE-2025-68617
Published
Dec 23, 2025
Updated
Dec 24, 2025
Vendor
FluidSynth
Product
FluidSynth
Classifications
CWE-416
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 23, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 24, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.5.0, < 2.5.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

FluidSynth · FluidSynthversion=>= 2.5.0, < 2.5.2

Published CVSS scores

7.0GitHubCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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