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Wasmtime CVE-2022-39394

CRITICAL
Out-of-bounds Write (CWE-787)
2022-11-10 security-advisories@github.com
9.8
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.

Exploit ScenarioDerived

A remote attacker could write data beyond allocated buffer boundaries leading to code execution or crashes by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAI

Wasmtime is a standalone runtime for WebAssembly. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Out-of-bounds Write vulnerability could allow attackers to write data beyond allocated buffer boundaries leading to code execution or crashes.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Validate write boundaries, use memory-safe languages, enable compiler protections (ASLR, stack canaries).

Affected Packages

cargo wasmtime fix: 1.0.2, 2.0.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in cargo

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Out-of-bounds Write (CWE-787), which allows attackers to write data beyond allocated buffer boundaries leading to code execution or crashes. Wasmtime is a standalone runtime for WebAssembly. Prior to version 2.0.2, there is a bug in Wasmtime's C API implementation where the definition of the wasmtime_trap_code does not match its declared signature in the wasmtime/trap.h header file. This discrepancy causes the function implementation to perform a 4-byte write into a 1-byte buffer provided by the caller. This can lead to three zero bytes being written beyond the 1-byte location provided by the caller. This bug has been patched and users should upgrade to Wasmtime 2.0.2. This bug can be worked around by providing a 4-byte buffer casted to a 1-byte buffer when calling wasmtime_trap_code. Users of the wasmtime crate are not affected by this issue, only users of the C API function wasmtime_trap_code are affected. Affected products include: Bytecodealliance Wasmtime. Version information: version 2.0.2.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

Wasmtime is a standalone runtime for WebAssembly. Prior to version 2.0.2, there is a bug in Wasmtime's C API implementation where the definition of the wasmtime_trap_code does not match its declared signature in the wasmtime/trap.h header file. This discrepancy causes the function implementation to perform a 4-byte write into a 1-byte buffer provided by the caller. This can lead to three zero bytes being written beyond the 1-byte location provided by the caller. This bug has been patched and users should upgrade to Wasmtime 2.0.2. This bug can be worked around by providing a 4-byte buffer casted to a 1-byte buffer when calling wasmtime_trap_code. Users of the wasmtime crate are not affected by this issue, only users of the C API function wasmtime_trap_code are affected.

Threat Intelligence Overview

EPSS Score
0.3%
Top 77% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Affected Products (CPE)NVD

cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*
cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*
CVE-2026-115889 CRITICAL POC
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Wasmtime versions before 36.0.19, and the 37.0.0 through 42.x line, can silently miscompile attacker-supplied WebAssembl

CVE-2026-115893 CRITICAL POC
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Sandbox escape in Wasmtime on aarch64 lets a user-supplied WebAssembly module redirect an oversized br_table branch to a

CVE-2023-26489 CRITICAL
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CVE-2022-24791 CRITICAL
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Wasmtime is a standalone JIT-style runtime for WebAssembly, using Cranelift. Rated critical severity (CVSS 9.8), this vu

CVE-2024-30266 MEDIUM POC
5.5 Apr 04

wasmtime is a runtime for WebAssembly. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. Pu

CVE-2026-34987 CRITICAL
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Memory sandbox escape in Wasmtime's Winch compiler (versions 25.0.0 to before 36.0.7, 42.0.2, 43.0.1) enables authentica

CVE-2026-34971 CRITICAL
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Arbitrary memory read/write vulnerability in Bytecode Alliance Wasmtime versions 32.0.0 through 36.0.6, 42.0.0-42.0.1, a

CVE-2023-30624 HIGH
8.8 Apr 27

Wasmtime is a standalone runtime for WebAssembly. Rated high severity (CVSS 8.8), this vulnerability is remotely exploit

CVE-2022-31146 HIGH
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Wasmtime is a standalone runtime for WebAssembly. Rated high severity (CVSS 8.8), this vulnerability is remotely exploit

CVE-2022-39393 HIGH
8.6 Nov 10

Wasmtime is a standalone runtime for WebAssembly. Rated high severity (CVSS 8.6), this vulnerability is remotely exploit

CVE-2026-27572 HIGH
7.5 Feb 24

Wasmtime's HTTP header handling in the wasmtime-wasi-http crate crashes when processing excessive header fields, allowin

CVE-2026-27195 HIGH
7.5 Feb 24

Wasmtime versions 39.0.0 and later experience a denial-of-service panic when async WebAssembly component functions are c

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