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Fencer Vulns
medium 5.1

CVE-2022-23636 json

Invalid drop of partially-initialized instances in wasmtime

published 2022-02-16 4 y ago modified 2026-10-12 27 d ago also CVE-2022-31169 , GHSA-7f6x-jwh5-m9r4 , GHSA-88xq-w8cq-xfg7 , RUSTSEC-2022-0096 , RUSTSEC-2022-0101 , EUVD-2022-0913

cvss
5.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

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.

Patch / fix

  • crates.io wasmtime 0.33.1, 0.34.1, 0.38.2
  • crates.io cranelift-codegen 0.85.2
  • bytecodealliance wasmtime 0.33.1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

0.77% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.1 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.1 AV:N/AC:M/Au:N/C:N/I:N/A:C
GitHub 3.1 5.1 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
crates.io wasmtime
>=0.34.0, <0.34.1
<0.33.1
<0.38.2
>=0.0.0-0, <0.33.1
>=0.0.0-0, <0.38.2
0.34.1
0.33.1
0.38.2
crates.io cranelift-codegen
<0.85.2
0.85.2

Affected products

  • bytecodealliance wasmtime

Classification

Weakness
  • CWE-824 Access of Uninitialized Pointer
  • CWE-682 Incorrect Calculation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.