CVE-2026-23833

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 80% of all CVEs by exploit prediction. 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: epss, nvd
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: Elevated riskExposed: 0

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

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.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

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
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
23%
KEV
Not listed

Published

January 19, 2026

Last Modified

June 17, 2026

Advisory Details (4)

Auto-updated Aug 2, 2026
Patch available. Sources: github_commit, github_pr, github.
github Patch Available

Denial-of-service via out-of-bounds check bypass in the API component · Advisory · esphome/esphome · GitHub

https://github.com/esphome/esphome/security/advisories/GHSA-4h3h-63v6-88qx
github_pr Patch Available

[api] Use subtraction for protobuf bounds checking

Patch available: esphome/esphome 2026.4.2 (PR #13306 merged 2026-01-17)

https://github.com/esphome/esphome/pull/13306
github_commit Patch Available

commit 69d7b6e92103 (esphome/esphome)

Patch available: esphome/esphome 2026.4.2 (contains commit 69d7b6e92103)

https://github.com/esphome/esphome/commit/69d7b6e9210390051318bd8e6410727689de08d6
generic

Security Best Practices - ESPHome - Smart Home Made Simple

https://esphome.io/guides/security_best_practices

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
esphome2025.10.0 ... 2025.9.3 (37 versions)2025.12.7—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 25× 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.

Showing the most recent 100 of 156 total refreshes for this CVE.

  1. 2026-09-19 03:00 UTCOSV refresh
  2. 2026-09-18 19:27 UTCEPSS rescore
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  1. 2026-08-19 17:03 UTCEPSS rescore
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  74. 2026-06-29 14:06 UTCEPSS rescore
  75. 2026-06-28 14:07 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-23833?
CVE-2026-23833 is a high vulnerability published on January 19, 2026. 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 + fieldlength > end in…
When was CVE-2026-23833 disclosed?
CVE-2026-23833 was first published in the National Vulnerability Database on January 19, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23833 actively exploited?
CVE-2026-23833 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 76.6% of all scored CVEs.
What is the CVSS score of CVE-2026-23833?
CVE-2026-23833 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-23833?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23833, 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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