UBUNTU-CVE-2026-61723 (CVE-2026-61723)
Vulnerability from osv_ubuntu – Published: 2026-09-18 20:17 – Updated: 2026-09-23 23:31 – Source website
VLAI
Details
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.
Severity
6.8 (Medium)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "fluidsynth",
"binary_version": "1.1.6-2"
},
{
"binary_name": "libfluidsynth1",
"binary_version": "1.1.6-2"
}
]
},
"package": {
"ecosystem": "Ubuntu:14.04:LTS",
"name": "fluidsynth",
"purl": "pkg:deb/ubuntu/fluidsynth@1.1.6-2?arch=source\u0026distro=trusty"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.1.6-2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "fluidsynth",
"binary_version": "1.1.6-3"
},
{
"binary_name": "libfluidsynth1",
"binary_version": "1.1.6-3"
}
]
},
"package": {
"ecosystem": "Ubuntu:16.04:LTS",
"name": "fluidsynth",
"purl": "pkg:deb/ubuntu/fluidsynth@1.1.6-3?arch=source\u0026distro=xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.1.6-2build1",
"1.1.6-3"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "fluidsynth",
"binary_version": "1.1.9-1"
},
{
"binary_name": "libfluidsynth1",
"binary_version": "1.1.9-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:18.04:LTS",
"name": "fluidsynth",
"purl": "pkg:deb/ubuntu/fluidsynth@1.1.9-1?arch=source\u0026distro=bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.1.6-4",
"1.1.8-1",
"1.1.8-2",
"1.1.8-3",
"1.1.9-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "fluidsynth",
"binary_version": "2.1.1-2"
},
{
"binary_name": "libfluidsynth2",
"binary_version": "2.1.1-2"
}
]
},
"package": {
"ecosystem": "Ubuntu:20.04:LTS",
"name": "fluidsynth",
"purl": "pkg:deb/ubuntu/fluidsynth@2.1.1-2?arch=source\u0026distro=focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.1.11-4",
"1.1.11-4ubuntu1",
"2.1.0-1",
"2.1.1-2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "fluidsynth",
"binary_version": "2.2.5-1"
},
{
"binary_name": "libfluidsynth3",
"binary_version": "2.2.5-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "fluidsynth",
"purl": "pkg:deb/ubuntu/fluidsynth@2.2.5-1?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.1.7-1.1",
"2.2.4-2",
"2.2.5-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "fluidsynth",
"binary_version": "2.3.4-1build3"
},
{
"binary_name": "libfluidsynth3",
"binary_version": "2.3.4-1build3"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "fluidsynth",
"purl": "pkg:deb/ubuntu/fluidsynth@2.3.4-1build3?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.3.3-2.1",
"2.3.4-1",
"2.3.4-1build1",
"2.3.4-1build2",
"2.3.4-1build3"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "fluidsynth",
"binary_version": "2.4.8+dfsg-1"
},
{
"binary_name": "libfluidsynth3",
"binary_version": "2.4.8+dfsg-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "fluidsynth",
"purl": "pkg:deb/ubuntu/fluidsynth@2.4.8+dfsg-1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.4.7+dfsg-2",
"2.4.8+dfsg-1"
]
}
],
"aliases": [],
"details": "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.",
"id": "UBUNTU-CVE-2026-61723",
"modified": "2026-09-23T23:31:26Z",
"published": "2026-09-18T20:17:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-61723"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-61723"
},
{
"type": "REPORT",
"url": "https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-r4mc-v3p8-pv47"
}
],
"related": [],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-61723"
]
}
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Sightings
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vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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