CVE-2022-23636 [Medium] | Security Vulnerability in Wasmtime

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.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-17	0.74%	0.76%	+0.02%
2	2026-06-15	0.30%	0.74%	+0.44%
3	2026-06-10	—	0.30%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-17

0.74%

0.76%

+0.02%

2026-06-15

0.30%

0.74%

+0.44%

2026-06-10

—

0.30%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.1	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.4	3.6	[email protected]
8.1	3.1	HIGH	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.2	5.9	[email protected]
7.1	2.0	HIGH	`AV:N/AC:M/Au:N/C:N/I:N/A:C` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:C) Complete availability impact.	8.6	6.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.1

3.1

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.4

3.6

[email protected]

8.1

3.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.2

5.9

[email protected]

7.1

2.0

HIGH

AV:N/AC:M/Au:N/C:N/I:N/A:C Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:C): Complete availability impact.

8.6

6.9

[email protected]

GitHub Security Advisory for CVE-2022-23636

GHSA-88xq-w8cq-xfg7 · Severity: medium · Ecosystem: rust — Invalid drop of partially-initialized instances in the pooling instance allocator for modules with defined `externref` globals

OS Trackers for CVE-2022-23636

vendor	priority	summary	link
`debian`	unimportant	CVE-2022-23636 unimportant priority: Debian including 1 source packages (rust-wasmtime), 3 status rows across 3 suites (forky, sid, trixie): resolved 3.	https://security-tracker.debian.org/tracker/CVE-2022-23636

Affected software / configurations for CVE-2022-23636

Vendor	Product	Version	Raw CPE
bytecodealliance	wasmtime	< 0.33.1	cpe:2.3:a:bytecodealliance:wasmtime::::::rust::*
bytecodealliance	wasmtime	0.34.0	cpe:2.3:a:bytecodealliance:wasmtime:0.34.0:::::rust::

References for CVE-2022-23636

URL	Tags
https://github.com/bytecodealliance/wasmtime/commit/886ecc562040bef61faf19438c22285c2d62403a	Patch Third Party Advisory
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-88xq-w8cq-xfg7	Mitigation Third Party Advisory

URL

CVE-2022-23636 | Invalid drop of partially-initialized instances in wasmtime

Exploit prediction scoring system (EPSS) score for CVE-2022-23636

Common vulnerability scoring system (CVSS) metrics for CVE-2022-23636

Weakness enumeration for CVE-2022-23636

GitHub Security Advisory for CVE-2022-23636

OS Trackers for CVE-2022-23636

Affected software / configurations for CVE-2022-23636

References for CVE-2022-23636