What is the CVSS score of CVE-2026-23833?

CVE-2026-23833 has a contested CVSS base score of 7.5 from a third party (e.g. CISA-ADP), while the vendor rates it High. vuln.today uses the vendor rating as authoritative.

How to fix or mitigate CVE-2026-23833?

Within 7 days: Identify all affected systems running versions 2025.9.0 and apply vendor patches promptly. Vendor patch is available.

Esphome CVE-2026-23833

HIGH

Integer Overflow or Wraparound (CWE-190)

2026-01-19 security-advisories@github.com

GHSA-4h3h-63v6-88qx

Denial Of Service Integer Overflow Red Hat Esphome

High

Disputed · 7.5 NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Craft malicious protobuf message with oversized field_length
Exploit

Send to ESPHome API without encryption
Execution

Integer overflow bypasses bounds check
Impact

Device reads invalid memory and crashes

Vulnerability Assessment

Weakness	CWE CWE-190 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Integer overflow checks MITRE ATT&CK 1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	ESPHome versions 2025.9.0 through 2025.12.6 with API encryption disabled. Attacker must have network access to the ESPHome device's API port (default 6053). No authentication required when encryption is not enabled.
Impact	CVSS 7.5 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Exploitation no authentication required. Exploitable via remote/network.
Exploit ScenarioDerived	A remote attacker without authentication could exploit this vulnerability to compromise the affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

ESPHome versions 2025.9.0 through 2025.12.6 are vulnerable to a denial-of-service attack via integer overflow in the API protobuf decoder, affecting all supported microcontroller platforms (ESP32, ESP8266, RP2040, LibreTiny). Unauthenticated attackers can crash ESPHome devices by sending specially crafted packets with large field length values to bypass bounds checking when API encryption is disabled. Upgrade to version 2025.12.7 or later to remediate.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:54 CVSS 7.5

RemediationAI

A vendor patch is available — apply it immediately. Restrict network access to the affected service where possible.

Affected Packages

pypi esphome fix: 2025.12.7

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in pypi

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Classified as CWE-190 (Integer Overflow or Wraparound). Affects the API component of Esphome. ESPHome is a system to control microcontrollers remotely through Home Automation systems. In versions 2025.9.0 through 2025.12.6, an integer overflow in the API component's protobuf decoder allows denial-of-service attacks when API encryption is not used. The bounds check ptr + field_length > end in components/api/proto.cpp can overflow when a malicious client sends a large field_length value. This affects all ESPHome device platforms (ESP32, ESP8266, RP2040, LibreTiny). The overflow bypas

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Sources disagree (Low–High)

GitHub Advisory PRIMARY 7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Red Hat 7.5 LOW

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Patch released

Mar 04, 2026 - 15:02 nvd

Patch available

CVE Published

Jan 19, 2026 - 18:16 nvd

HIGH 7.5

DescriptionGitHub Advisory

ESPHome is a system to control microcontrollers remotely through Home Automation systems. In versions 2025.9.0 through 2025.12.6, an integer overflow in the API component's protobuf decoder allows denial-of-service attacks when API encryption is not used. The bounds check ptr + field_length > end in components/api/proto.cpp can overflow when a malicious client sends a large field_length value. This affects all ESPHome device platforms (ESP32, ESP8266, RP2040, LibreTiny). The overflow bypasses the out-of-bounds check, causing the device to read invalid memory and crash. When using the plaintext API protocol, this attack can be performed without authentication. When noise encryption is enabled, knowledge of the encryption key is required. Users should upgrade to ESPHome 2025.12.7 or later to receive a patch, enable API encryption with a unique key per device, and follow the Security Best Practices.

Executive ViewAI

Why It Matters

Organizations using versions 2025.9.0 face notable risk from CVE-2026-23833, a integer overflow vulnerability rated CVSS 7.5. Exploitation could allow attackers to corrupt memory, crash the application, or potentially execute arbitrary code. A patch is available and should be applied as part of regular vulnerability management.

Business Impact: High

Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score

0.1%

Top 78% exploitable

Data Quality

4 sources

Confidence: Medium

NVD

CVE.org

EPSS Vendor

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.1%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.