How severe is CVE-2026-23833?

No CVSS score has been assigned to CVE-2026-23833 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-23833?

CVE-2026-23833 affects the following packages: esphome (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-23833?

Update esphome to 2025.12.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23833 is resolved across your whole dependency graph.

How do I detect CVE-2026-23833 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for esphome. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-23833 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-23833?

O3 pinpoints whether CVE-2026-23833 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-23833 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-23833 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-23833?

CVE-2026-23833 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 19th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2026-23833 published, and has it been updated?

CVE-2026-23833 was published on January 19, 2026 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-23833: esphome

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk19th percentile+0.18%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐍esphome

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`esphome`	≥ 2025.9.0&&< 2025.12.7	2025.12.7

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for esphome. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update esphome to 2025.12.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23833 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-23833 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-23833. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 pla

O3 Security · Impact-Aware SCA

Is CVE-2026-23833 in your dependencies?

O3 detects CVE-2026-23833 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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CVE-2026-23833