CVE-2025-40930Public exploitNetwork attack vector

Process crash via floating-point parser overread

Published Sep 8, 2025 · Updated Nov 4, 2025

Heap-based buffer overflow in JSON::SIMD before 1.07 allows remote attackers to crash a consuming process with crafted JSON. The legacy decoder's recursive json_atof_scan1 floating-point parser advances beyond allocated input when a crafted number contains a second decimal point. Exposure requires attacker-controlled JSON to reach the legacy decoder, or a nondefault USE_LONG_DOUBLE or USE_QUADMATH build to invoke its fallback parser.

CVSS severity7.5
High
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in JSON::SIMD before 1.07 allows remote attackers to crash a consuming process with crafted JSON. The legacy decoder's recursive json_atof_scan1 floating-point parser advances beyond allocated input when a crafted number contains a second decimal point. Exposure requires attacker-controlled JSON to reach the legacy decoder, or a nondefault USE_LONG_DOUBLE or USE_QUADMATH build to invoke its fallback parser.

The record

CVE
CVE-2025-40930
Published
Sep 8, 2025
Updated
Nov 4, 2025
Vendor
Juhász Péter
Product
JSON::SIMD
Classifications
CWE-122, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 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=0 <1.07

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juhász Péter · JSON::SIMDversion=0 <1.07

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1499.004Application or System Exploitation

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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