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CVE-2022-24791

Published: 31 March 2022

Wasmtime is a standalone JIT-style runtime for WebAssembly, using Cranelift. There is a use after free vulnerability in Wasmtime when both running Wasm that uses externrefs and enabling epoch interruption in Wasmtime. If you are not explicitly enabling epoch interruption (it is disabled by default) then you are not affected. If you are explicitly disabling the Wasm reference types proposal (it is enabled by default) then you are also not affected. The use after free is caused by Cranelift failing to emit stack maps when there are safepoints inside cold blocks. Cold blocks occur when epoch interruption is enabled. Cold blocks are emitted at the end of compiled functions, and change the order blocks are emitted versus defined. This reordering accidentally caused Cranelift to skip emitting some stack maps because it expected to emit the stack maps in block definition order, rather than block emission order. When Wasmtime would eventually collect garbage, it would fail to find live references on the stack because of the missing stack maps, think that they were unreferenced garbage, and therefore reclaim them. Then after the collection ended, the Wasm code could use the reclaimed-too-early references, which is a use after free. Patches have been released in versions 0.34.2 and 0.35.2, which fix the vulnerability. All Wasmtime users are recommended to upgrade to these patched versions. If upgrading is not an option for you at this time, you can avoid the vulnerability by either: disabling the Wasm reference types proposal, config.wasm_reference_types(false); or by disabling epoch interruption if you were previously enabling it. config.epoch_interruption(false).

Priority

Medium

CVSS 3 base score: 9.8

Status

Package Release Status
firefox
Launchpad, Ubuntu, Debian
bionic Needed

focal Needed

impish Needed

jammy
Released (1:1snap1-0ubuntu1)
trusty Does not exist

upstream Needs triage

xenial Needed

mozjs38
Launchpad, Ubuntu, Debian
bionic Needs triage

focal Does not exist

impish Does not exist

jammy Does not exist

trusty Does not exist

upstream Needs triage

xenial Does not exist

mozjs52
Launchpad, Ubuntu, Debian
bionic Needs triage

focal Needs triage

impish Does not exist

jammy Does not exist

trusty Does not exist

upstream Needs triage

xenial Does not exist

mozjs68
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Needs triage

impish Does not exist

jammy Does not exist

trusty Does not exist

upstream Needs triage

xenial Does not exist

mozjs78
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Does not exist

impish Needs triage

jammy Needs triage

trusty Does not exist

upstream Needs triage

xenial Does not exist

mozjs91
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Does not exist

impish Does not exist

jammy Needs triage

trusty Does not exist

upstream Needs triage

xenial Does not exist

thunderbird
Launchpad, Ubuntu, Debian
bionic Needed

focal Needed

impish Needed

jammy Needed

trusty Does not exist

upstream Needs triage

xenial Needed