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Home CVE Database CVE-2021-39218

CVE-2021-39218

Description

Wasmtime is an open source runtime for WebAssembly & WASI. In Wasmtime from version 0.26.0 and before version 0.30.0 is affected by a memory unsoundness vulnerability. There was an invalid free and out-of-bounds read and write bug when running Wasm that uses `externref`s in Wasmtime. To trigger this bug, Wasmtime needs to be running Wasm that uses `externref`s, the host creates non-null `externrefs`, Wasmtime performs a garbage collection (GC), and there has to be a Wasm frame on the stack that is at a GC safepoint where there are no live references at this safepoint, and there is a safepoint with live references earlier in this frame\'s function. Under this scenario, Wasmtime would incorrectly use the GC stack map for the safepoint from earlier in the function instead of the empty safepoint. This would result in Wasmtime treating arbitrary stack slots as `externref`s that needed to be rooted for GC. At the *next* GC, it would be determined that nothing was referencing these bogus `externref`s (because nothing could ever reference them, because they are not really `externref`s) and then Wasmtime would deallocate them and run `::drop` on them. This results in a free of memory that is not necessarily on the heap (and shouldn\'t be freed at this moment even if it was), as well as potential out-of-bounds reads and writes. Even though support for `externref`s (via the reference types proposal) is enabled by default, unless you are creating non-null `externref`s in your host code or explicitly triggering GCs, you cannot be affected by this bug. We have reason to believe that the effective impact of this bug is relatively small because usage of `externref` is currently quite rare. This bug has been patched and users should upgrade to Wasmtime version 0.30.0. If you cannot upgrade Wasmtime at this time, you can avoid this bug by disabling the reference types proposal by passing `false` to `wasmtime::Config::wasm_reference_types`.

Priority: --
CVSS v3: 6.3
Component: It doesn\'t impact WRLinux.
Publish Date: Sep 17, 2021
Related ID: --
CVSS v2: MEDIUM
Modified Date: Sep 17, 2021

Find out more about CVE-2021-39218 from the MITRE-CVE dictionary and NIST NVD


Products Affected

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Product Name Status Defect Fixed Downloads
Linux
Wind River Linux LTS 17 Not Vulnerable -- -- --
Wind River Linux 8 Not Vulnerable -- -- --
Wind River Linux 9 Not Vulnerable -- -- --
Wind River Linux 7 Not Vulnerable -- -- --
Wind River Linux LTS 21 Not Vulnerable -- -- --
Wind River Linux LTS 22 Not Vulnerable -- -- --
Wind River Linux LTS 18 Not Vulnerable -- -- --
Wind River Linux LTS 19 Not Vulnerable -- -- --
Wind River Linux CD release Not Vulnerable -- -- --
Wind River Linux 6 Not Vulnerable -- -- --
Wind River Linux LTS 23 Not Vulnerable -- -- --
VxWorks
VxWorks 7 Not Vulnerable -- -- --
VxWorks 6.9 Not Vulnerable -- -- --
Helix Virtualization Platform Cert Edition
Helix Virtualization Platform Cert Edition Not Vulnerable -- -- --

Related Products

Product Name Status Defect Fixed Downloads

Notes
Requires LTSS - customers must have active LTSS (Long Term Security Shield) Support to receive up-to-date information about vulnerabilities that may affect legacy software. Please contact your Wind River account team or see https://docs.windriver.com/bundle/Support_and_Maintenance_Supplemental_Terms_and_Conditions and https://support2.windriver.com/index.php?page=plc for more information.
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