Security readout for executives and security teams
Plain-English summary
Wasmtime may mishandle WebAssembly reference values during garbage collection. Under specific conditions, memory that is still in use can be freed and then reused, creating a use-after-free risk. The issue is important where untrusted or tenant-supplied WebAssembly runs in Wasmtime, but the published scoring indicates high attack complexity.
Executive priority
Treat as a moderate-priority platform runtime issue. Escalate if Wasmtime is used for untrusted WebAssembly workloads, because the impact includes potential confidentiality loss. For internal-only trusted WebAssembly, handle through normal dependency remediation timelines unless local risk factors increase exposure.
Technical view
The bug is in Wasmtime's Cranelift code generator. Functions using WebAssembly reference types may miss metadata needed by runtime GC, causing live GC references to be reclaimed and later used. It was introduced with the regalloc2 migration in Wasmtime 0.37.0 and is classified as CWE-416 with CVSS 6.4.
Likely exposure
Exposure is most likely in services embedding Wasmtime to execute untrusted, customer-supplied, or sandboxed WebAssembly with reference types enabled. Affected ranges listed are >=0.37.0 <0.38.2 and >=0.84.0 <0.85.2. Deployments not using Wasmtime or not enabling reference types are less likely exposed.
Exploitation context
The source bundle does not show CISA KEV listing or cited active exploitation. The CVSS vector indicates network reachability, low privileges, no user interaction, and high attack complexity. Practical exploitation depends on an attacker being able to run suitable WebAssembly in an affected Wasmtime environment.
Researcher notes
Key evidence is the vendor advisory and CVE record. The root cause is missing GC metadata for reference-typed functions in Cranelift after regalloc2 migration. The bundle names mitigations and affected ranges, but does not provide exploit details or evidence of exploitation in the wild.
Mitigation direction
- Upgrade Wasmtime to 0.38.2 or a fixed branch version such as 0.85.2.
- Disable WebAssembly reference types using wasmtime::Config::wasm_reference_types(false).
- If upgrade is not immediately possible, downgrade to Wasmtime 0.36.0 or earlier.
- Prioritize remediation for systems running untrusted or multi-tenant WebAssembly.
- Check Bytecode Alliance advisory for branch-specific guidance before deployment.
Validation and detection
- Inventory applications and services embedding Wasmtime.
- Confirm deployed Wasmtime versions against the affected ranges.
- Check whether reference types are enabled in runtime configuration.
- Identify whether untrusted users can submit or influence WebAssembly modules.
- Run existing unit and integration tests after upgrading or changing runtime configuration.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-416: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2022-31146 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L1.64.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.4MediumVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-5fhj-g3p3-pq9gCVE reference · x_refsource_CONFIRM
- https://github.com/WebAssembly/reference-typesCVE reference · x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.