CVE-2022-31146: Use After Free in Wasmtime
There is a bug in Wasmtime's code generator, Cranelift, where functions using reference types may be incorrectly missing metadata required for runtime garbage collection (GC). This means that if a GC happens at runtime then the collector will mistakenly think some Wasm stack frames do not have live references to garbage collected values and therefore reclaim and deallocate them. The function can then subsequently continue to use the values, leading later to use-after-free bugs. This bug was introduced in Cranelift's migration to the regalloc2 register allocator in the Wasmtime 0.37.0 release on 2022-05-20. This bug has been patched and users should upgrade to Wasmtime version 0.38.2.
Mitigations for this issue can be achieved by doing one of:
Disabling the reference types proposal by passing false to wasmtime::Config::wasmreferencetypes. Downgrading to Wasmtime 0.36.0 or prior.
Other sources
Wasmtime is a standalone runtime for WebAssembly. There is a bug in the Wasmtime's code generator, Cranelift, where functions using reference types may be incorrectly missing metadata required for runtime garbage collection. This means that if a GC happens at runtime then the GC pass will mistakenly think these functions do not have live references to GC'd values, reclaiming them and deallocating them. The function will then subsequently continue to use the values assuming they had not been GC'd, leading later to a use-after-free. This bug was introduced in the migration to the regalloc2 register allocator that occurred in the Wasmtime 0.37.0 release on 2022-05-20. This bug has been patched and users should upgrade to Wasmtime version 0.38.2. Mitigations for this issue can be achieved by disabling the reference types proposal by passing false to wasmtime::Config::wasmreferencetypes or downgrading to Wasmtime 0.36.0 or prior.
Affected Software
Event History
Frequently Asked Questions
What is the vulnerability ID for this bug in Wasmtime's code generator Cranelift?
The vulnerability ID for this bug in Wasmtime's code generator Cranelift is CVE-2022-31146.
What is Wasmtime?
Wasmtime is a standalone runtime for WebAssembly.
What is the bug in Wasmtime's code generator Cranelift?
The bug in Wasmtime's code generator Cranelift is where functions using reference types may be missing required metadata for runtime garbage collection.
What is the severity of CVE-2022-31146?
The severity of CVE-2022-31146 is high with a CVSS score of 8.8.
How can I fix the vulnerability in Cranelift codegen and Wasmtime?
To fix the vulnerability in Cranelift codegen and Wasmtime, update to a version between 0.84.0 and 0.85.1 for Cranelift codegen, and between 0.37.0 and 0.38.1 for Wasmtime.