CVE-2026-54786
MediumCVSS 5.0Exploitation Probability (EPSS)
Low risk12th percentile — higher than 12% of all known CVEs
Summary
Wasmtime prior to versions 24.0.10, 36.0.11, 44.0.3, and 45.0.2 contains a vulnerability in the native WASIp1 implementation where the fd_renumber function fails to properly close the target file descriptor. This causes resource leaks in the host system, potentially leading to exhaustion of file descriptors and resources.
Risk Assessment
The organization is at risk of a resource exhaustion attack leading to denial of service (DoS) in the WebAssembly runtime. An attacker can repeatedly call fd_renumber in a loop to exhaust host file descriptors and memory.
Recommendation
Immediately upgrade Wasmtime to version 24.0.10, 36.0.11, 44.0.3, or 45.0.2 depending on your branch. If upgrading is not possible, restrict file access operations in WASM modules.
Original NVD description (English source)
Wasmtime is a runtime for WebAssembly. All versions prior to 24.0.10; versions 25.0.0 through those before 36.0.11; versions 37.0.0 through those before 44.0.3; and versions 45.0.0 and 45.0.1 contain a native implementation of WASIp1 which suffers from a leak in the fd_renumber function where the file descriptor being renumbered to is not properly closed. Wasmtime's implementation erroneously only updated the table of descriptors for WASIp1 and didn't update the underlying table of descriptors used by the host. This behavior means that while fd_renumber works correctly from a guest's perspective it ends up leaking resources in the host that aren't cleaned up until the corresponding Store is destroyed. In a loop, guests can use fd_renumber to cause hosts to exhaust both resources and file descriptors. This bug only affects the native implementation of WASIp1, meaning that only runtimes which load core wasm modules and expose fd_renumber are affected. Runtimes are additionally only affected if they expose the ability to acquire a file descriptor, such as opening a file. For runtimes that deny access to files they are unaffected. This issue has been fixed in versions 24.0.10, 36.0.11, 44.0.3, and 45.0.2.