CVE-2026-23833: ESPHome is a system to control microcontrollers remotely through Home Automation systems

Routine

HIGH 7.5REMOTEUPGRADE

CVE-2026-23833 is a high-severity flaw (CVSS 7.5) affecting esphome. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 (ESP3

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 77%)
CISA exploited list	No
Weakness	CWE-190
Published	2026-01-19
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: esphome

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-01-19 18:16 UTCPublished CVE record published
2026-06-17 10:22 UTCUpdated Record last modified

esphome esphome UPGRADE

Affected: >= 2025.9.0 and < 2025.12.7

Fixed in: 2025.12.7

Safe to downgrade to: a release before 2025.9.0

1. Check installed version

apt-cache policy esphome || rpm -q esphome || esphome --version

2. UPGRADE to 2025.12.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade esphome

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade esphome

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2025.9.0 (Debian / Ubuntu)

apt-cache madison esphome sudo apt install esphome=<VERSION_BEFORE_2025.9.0> sudo apt-mark hold esphome

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list esphome sudo dnf downgrade esphome-<VERSION_BEFORE_2025.9.0> sudo dnf versionlock add esphome

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-23833?

esphome: upgrade to 2025.12.7. Exact commands for each OS are on this page.

Is CVE-2026-23833 being exploited?

CVE-2026-23833 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-23833 affect?

CVE-2026-23833 affects esphome. Severity is high (CVSS 7.5). 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 encrypti

How urgent is CVE-2026-23833?

Priority 37/100. High severity; Remotely exploitable, no login, no user action

References

← Back to latest CVEs