CVE-2026-23833
Description
A flaw was found in ESPHome. An integer overflow vulnerability exists in the API component's protobuf decoder. A remote attacker can exploit this by sending a specially crafted, large field_length value, which bypasses a bounds check. This can lead to a denial-of-service (DoS) condition, causing the affected device to crash. This attack can be performed without authentication if API encryption is not utilized.
Statement
This vulnerability is rated Low for Red Hat. The flaw in ESPHome's API component, affecting python-aioesphomeapi in Fedora 42, can lead to a denial of service. Exploitation requires the API encryption to be disabled; if encryption is enabled, knowledge of the encryption key is necessary.
Mitigation
To mitigate this issue, enable API encryption with a unique key for each ESPHome device. This prevents unauthenticated denial-of-service attacks by requiring knowledge of the encryption key for exploitation. Refer to ESPHome's Security Best Practices for detailed configuration instructions.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (Memory); DoS: Instability
This weakness can generally lead to undefined behavior and therefore crashes. When the calculated result is used for resource allocation, this weakness can cause too many (or too few) resources to be allocated, possibly enabling crashes if the product requests more resources than can be provided.
Integrity
Technical Impact: Modify Memory
If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the overflow/wraparound results in other conditions such as buffer overflows, further memory corruption may occur.
Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism
This weakness can sometimes trigger buffer overflows, which can be used to execute arbitrary code. This is usually outside the scope of the product's implicit security policy.
Availability,Other
Technical Impact: Alter Execution Logic; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)
If the overflow/wraparound occurs in a loop index variable, this could cause the loop to terminate at the wrong time - too early, too late, or not at all (i.e., infinite loops). With too many iterations, some loops could consume too many resources such as memory, file handles, etc., possibly leading to a crash or other DoS.
Access Control
Technical Impact: Bypass Protection Mechanism
If integer values are used in security-critical decisions, such as calculating quotas or allocation limits, integer overflows can be used to cause an incorrect security decision.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
