Vulnerability in Bytecodealliance Wasmtime
CVE-2022-23636
Wasmtime is an open source runtime for WebAssembly & WASI. Prior to versions 0.34.1 and 0.33.1, there exists a bug in the pooling instance allocator in Wasmtime's runtime where a failure to instantiate an instance for a module that defines an `externref` global will result in an invalid drop of a `VMExternRef` via an uninitialized pointer. A number of conditions listed in the GitHub Security Advisory must be true in order for an instance to be vulnerable to this issue. Maintainers believe that the effective impact of this bug is relatively small because the usage of `externref` is still uncommon and without a resource limiter configured on the `Store`, which is not the default configuration, it is only possible to trigger the bug from an error returned by `mprotect` or `VirtualAlloc`. Note that on Linux with the `uffd` feature enabled, it is only possible to trigger the bug from a resource limiter as the call to `mprotect` is skipped. The bug has been fixed in 0.34.1 and 0.33.1 and users are encouraged to upgrade as soon as possible. If it is not possible to upgrade to version 0.34.1 or 0.33.1 of the `wasmtime` crate, it is recommend that support for the reference types proposal be disabled by passing `false` to `Config::wasm_reference_types`. Doing so will prevent modules that use `externref` from being loaded entirely.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.1 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.008 (53.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 53.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000
Affected products
- Bytecodealliance Wasmtime — versions 0.34.0, < 0.33.0, = 0.34.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/bytecodealliance/wasmtime/security/advisories/GHSA-88xq-w8cq-xfg7 (Third Party Advisory, Mitigation)
- github.com/bytecodealliance/wasmtime/commit/886ecc562040bef61faf19438c22285c2d6… (Patch, Third Party Advisory)
Frequently asked questions
- What is CVE-2022-23636?
- CVE-2022-23636 is a medium-severity vulnerability in Bytecodealliance Wasmtime, classified under Access of Uninitialized Pointer. CVSS score: 5.1/10. Published 2022-02-16.
- How severe is CVE-2022-23636?
- Medium severity. CVSS v3 base score is 5.1 out of 10.
- Is CVE-2022-23636 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.