CWE-1303: Non-Transparent Sharing of Microarchitectural Resources

CWE-1303: Non-Transparent Sharing of Microarchitectural Resources is a Common Weakness Enumeration (CWE) entry maintained by MITRE. Hardware structures shared across execution contexts (e.g., caches and branch predictors) can violate the expected architecture isolation between contexts. Modern processors use techniques such as out-of-order execution, speculation, prefetching, data forwarding, and caching to increase performance. Details about the implementation of these techniques are hidden from the programmer's view. This is problematic when the hardware implementation of these techniques results in resources being shared across supposedly isolated contexts. Contention for shared resources between different contexts opens covert channels that allow malicious programs executing in one context to recover information from another context. Some examples of shared micro-architectural resources that have been used to leak information between contexts are caches, branch prediction logic, and load or store buffers. Speculative and out-of-order execution provides an attacker with increased control over which data is leaked through the covert channel. If the extent of resource sharing between contexts in the design microarchitecture is undocumented, it is extremely difficult to ensure system assets are protected against disclosure.

If exploited, CWE-1303 (Non-Transparent Sharing of Microarchitectural Resources) it can compromise Confidentiality, leading to outcomes such as Read Application Data and Read Memory.

Recommended mitigations for CWE-1303 include: Microarchitectural covert channels can be addressed using a mixture of hardware and software mitigation techniques. These include partitioned caches, new barrier and flush instructions, and disabling high resolution performance counters and timers. Microarchitectural covert channels can be addressed using a mixture of hardware and software mitigation techniques. These include partitioned caches, new barrier and flush instructions, and disabling high resolution performance counters and timers.

CWE-1303 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

A CWE (Common Weakness Enumeration) like CWE-1303 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.