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.
CVE-2026-23833
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 81% 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).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- 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 computedSeverity75% × 45%Exploitation40% × 40%Automatability100% × 15%Action: Remediate soon — notable exploitation risk. - EPSS
- 19.4%
- KEV
- Not listed
Published
January 19, 2026
Last Modified
March 4, 2026
References (4)
- security-advisories@githubhttps://esphome.io/guides/security_best_practices
- security-advisories@githubhttps://github.com/esphome/esphome/commit/69d7b6e9210390051318bd8e6410727689de08d6
- security-advisories@githubhttps://github.com/esphome/esphome/pull/13306
- security-advisories@githubhttps://github.com/esphome/esphome/security/advisories/GHSA-4h3h-63v6-88qx
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| esphome | 2025.10.0 ... 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 14× in last 7d / 54× 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.
- 2026-07-23 14:18 UTCEPSS rescore
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- 2026-06-17 16:35 UTCOSV refresh
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- 2026-05-29 15:41 UTCEG score recompute
- 2026-05-29 13:44 UTCEPSS rescore
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Related CVEs(same CWE)
Same CWE
10 shownCWE-190
- CVE-2009-0947EG 9.8CRITICAL
- CVE-2013-2729EG 9.8 KEVEPSS 99%CRITICAL
- CVE-2005-1141EG 9.8CRITICAL
- CVE-2005-0102EG 9.8CRITICAL
- CVE-2002-0391EG 9.8EPSS 99%CRITICAL
- CVE-2002-0639EG 9.8EPSS 97%CRITICAL
- CVE-2013-3486EG 9.6CRITICAL
- CVE-2013-2596NVD 7.8EG 9.0 KEVHIGH
- CVE-2012-5054NVD 8.8EG 9.0 KEVEPSS 97%HIGH
- CVE-2011-1823NVD 7.8EG 9.0 KEVEPSS 99%HIGH
Frequently asked(5)
What is CVE-2026-23833?
When was CVE-2026-23833 disclosed?
Is CVE-2026-23833 actively exploited?
What is the CVSS score of CVE-2026-23833?
How do I remediate CVE-2026-23833?
Dependency Blast Radius
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