CVE-2025-69209

Board memory corruption via unchecked floating-point precision

Published Jan 21, 2026 · Updated Jan 21, 2026

Stack buffer overflow in Arduino AVR Boards before 1.8.7 allows local users to corrupt memory through high-precision conversion. The WString float and double constructors pass caller-controlled decimalPlaces values to dtostrf, which writes past fixed-size stack buffers. Reaching the flaw requires locally executing firmware that supplies excessive precision; denial of service results directly, while code execution requires additional unspecified conditions.

CVSS severity6.9
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack buffer overflow in Arduino AVR Boards before 1.8.7 allows local users to corrupt memory through high-precision conversion. The WString float and double constructors pass caller-controlled decimalPlaces values to dtostrf, which writes past fixed-size stack buffers. Reaching the flaw requires locally executing firmware that supplies excessive precision; denial of service results directly, while code execution requires additional unspecified conditions.

The record

CVE
CVE-2025-69209
Published
Jan 21, 2026
Updated
Jan 21, 2026
Vendor
Arduino
Product
Arduino AVR Boards
Classifications
CWE-120, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 21, 2026Record 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=< 1.8.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Arduino · Arduino AVR Boardsversion=< 1.8.7

Published CVSS scores

6.9GitHub, Inc.CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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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