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Wasmtime vulnerable to Use After Free with `externref`s

Moderate severity GitHub Reviewed Published Jul 20, 2022 in bytecodealliance/wasmtime • Updated Jan 27, 2023

Package

cargo cranelift-codegen (Rust)

Affected versions

>= 0.84.0, < 0.85.2

Patched versions

0.85.2
cargo wasmtime (Rust)
>= 0.37.0, < 0.38.2
0.38.2

Description

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:

References

@alexcrichton alexcrichton published to bytecodealliance/wasmtime Jul 20, 2022
Published to the GitHub Advisory Database Jul 20, 2022
Reviewed Jul 20, 2022
Published by the National Vulnerability Database Jul 21, 2022
Last updated Jan 27, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L

EPSS score

0.232%
(62nd percentile)

Weaknesses

CVE ID

CVE-2022-31146

GHSA ID

GHSA-5fhj-g3p3-pq9g

Source code

Credits

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