CVE-2026-58264

CRITICALPre-NVD 9.89.8
EchelonGraph scoreLOW confidence

This critical-severity CVE scores 9.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: secondary
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 9.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 1.1.2 until 2.5.6, the FluidSynth command handler accepts a pitch_bend_range command whose channel argument is not bounds checked before the supplied value is written through the selected synth channel. An out-of-range channel can therefore cause an out-of-bounds heap write, leading to denial of service or possible code execution. The issue is remotely reachable when the TCP server is enabled through new_fluid_server() or fluidsynth -s, and it is locally reachable through malicious commands delivered to the FluidSynth shell on standard input. Applications that do not use the shell, command handler, or TCP server are not affected. This issue is fixed in version 2.5.6.

CVSS v3
9.8
EG Score
9.8(low)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
—
EPSS %ILE
—
KEV
Not listed

Published

September 18, 2026

Last Modified

September 18, 2026

Advisory Details (4)

Auto-updated Sep 18, 2026
Patch available. Sources: github_pr, github_release, github, github_commit.
github Patch Available

Heap-based buffer overrun in command handler · Advisory · FluidSynth/fluidsynth · GitHub

https://github.com/FluidSynth/fluidsynth/security/advisories/GHSA-mqmq-w63q-cj94
github_release Patch Available

fluidsynth 2.5.6

Patch available: FluidSynth/fluidsynth v2.5.6

https://github.com/FluidSynth/fluidsynth/releases/tag/v2.5.6
github_pr

fix: add channel bounds check in pitch_bend_range to prevent OOB access

Upstream fix in progress (PR #1796 · FluidSynth/fluidsynth, state=closed)

https://github.com/FluidSynth/fluidsynth/pull/1796
github_commit Patch Available

commit 762a3bd39a43 (FluidSynth/fluidsynth)

Patch available: FluidSynth/fluidsynth v2.5.6 (contains commit 762a3bd39a43)

https://github.com/FluidSynth/fluidsynth/commit/762a3bd39a431cd45abf3bbcce7286c87909d087

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 3× in last 7d / 3× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-18 20:30 UTCEG score recompute
  2. 2026-09-18 20:10 UTCEG score recompute
  3. 2026-09-18 20:09 UTCMITRE cvelistV5first tracked

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Frequently asked(4)

What is CVE-2026-58264?
CVE-2026-58264 is a critical vulnerability published on September 18, 2026. FluidSynth is a software synthesizer based on the SoundFont 2 specifications. From 1.1.2 until 2.5.6, the FluidSynth command handler accepts a pitchbendrange command whose channel argument is not bounds checked before the supplied value is written through the selected synth channel. An out-of-range…
When was CVE-2026-58264 disclosed?
CVE-2026-58264 was first published in the National Vulnerability Database on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-58264?
CVE-2026-58264 has a CVSS v3 base score of 9.8 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-58264?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-58264, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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