Security readout for executives and security teams
Plain-English summary
CVE-2026-23833 can let a network client crash ESPHome-managed microcontroller devices when the ESPHome native API is exposed without encryption. It does not indicate data theft or device takeover. Business impact is localized availability loss: affected sensors, switches, or controllers may reboot or become temporarily unavailable until recovered.
Executive priority
Treat as a routine availability fix unless ESPHome devices control critical operations or are reachable from untrusted networks. Prioritize patching exposed plaintext API deployments first, then complete upgrades during normal maintenance.
Technical view
ESPHome versions 2025.9.0 through 2025.12.6 contain an integer overflow in the API protobuf decoder. A large field_length can bypass the ptr + field_length > end bounds check, leading to invalid memory reads and device crash. Plaintext API use allows unauthenticated triggering; Noise encryption requires knowledge of the encryption key.
Likely exposure
Exposure is limited to ESPHome devices running 2025.9.0 through 2025.12.6 with the native API reachable by an attacker. Risk is higher where plaintext API is enabled or device APIs are reachable from untrusted networks.
Exploitation context
The advisory describes network-based denial of service. The CVE record marks KEV as false, and the provided sources do not claim active exploitation. Exploitation conditions differ by configuration: unauthenticated for plaintext API, key knowledge required when API encryption is enabled.
Researcher notes
The root issue is CWE-190 integer overflow in components/api/proto.cpp. The affected platforms listed are ESP32, ESP8266, RP2040, and LibreTiny. Review the GitHub advisory, pull request, and commit for patch details; avoid assuming broader product impact beyond ESPHome.
Mitigation direction
- Upgrade ESPHome to 2025.12.7 or later.
- Enable API encryption using a unique key per device.
- Follow ESPHome Security Best Practices guidance.
- Restrict ESPHome API access to trusted networks only.
Validation and detection
- Inventory ESPHome devices and record installed ESPHome versions.
- Identify devices running 2025.9.0 through 2025.12.6.
- Check whether the native API is enabled and reachable.
- Verify whether API encryption is enabled per device.
- Confirm upgraded devices report ESPHome 2025.12.7 or later.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-190: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-23833 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Low
- CVSS
- 1.7 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
1.7LowVector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/esphome/esphome/security/advisories/GHSA-4h3h-63v6-88qxCVE reference · x_refsource_CONFIRM
- https://github.com/esphome/esphome/pull/13306CVE reference · x_refsource_MISC
- https://github.com/esphome/esphome/commit/69d7b6e9210390051318bd8e6410727689de08d6CVE reference · x_refsource_MISC
- https://esphome.io/guides/security_best_practicesCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Integer Overflow or Wraparound
Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.