CVE-2022-31146 | Use After Free in Wasmtime

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::wasm_reference_types` or downgrading to Wasmtime 0.36.0 or prior.

Published: 2022-07-21 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-31146 is rated Moderate Risk (44.5/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.86%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2022-31146

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-25 0.76% 0.86% +0.09%
2 2026-06-10 0.41% 0.76% +0.35%
3 2026-06-01 — 0.41% —

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-31146

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.6 4.7 [email protected]
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]

Weakness enumeration for CVE-2022-31146

GitHub Security Advisory for CVE-2022-31146

GHSA-5fhj-g3p3-pq9g · Severity: medium · Ecosystem: rust — Wasmtime vulnerable to Use After Free with `externref`s

OS Trackers for CVE-2022-31146

vendor priority summary link
debian unimportant CVE-2022-31146 unimportant priority: Debian including 1 source packages (rust-wasmtime), 3 status rows across 3 suites (forky, sid, trixie): resolved 3. https://security-tracker.debian.org/tracker/CVE-2022-31146
ubuntu medium CVE-2022-31146 medium priority: Ubuntu including 7 source packages (firefox, mozjs38, …), 70 status rows across 10 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, trusty, upstream, xenial): DNE 41, ignored 22, not-affected 5, needs-triage 2. https://ubuntu.com/security/CVE-2022-31146

Affected software / configurations for CVE-2022-31146

Vendor Product Version Raw CPE
bytecodealliance cranelift-codegen >= 0.84.0, < 0.85.2 cpe:2.3:a:bytecodealliance:cranelift-codegen:*:*:*:*:*:rust:*:*
bytecodealliance wasmtime >= 0.37.0, < 0.38.2 cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*

References for CVE-2022-31146

cvelogic Threat Intelligence