CVE-2026-44216

ADVISORY - github

Summary

Impact

Wasmtime's allocation logic for a WebAssembly table contained checked arithmetic which panicked on overflow. This overflow is possible to trigger, and thus panic, when a table with an extremely large size is allocated. This is possible with the WebAssembly memory64 proposal where tables can have sizes in the 64-bit range as opposed to the previous 32-bit range which would not overflow. The panic happens when attempting to create a very large table, such as when instantiating a WebAssembly module or component.

This bug does not affect the pooling allocator which limits tables sizes to much less than the required amount to trigger the overflow. This bug is only present for the on-demand instance allocator, which is Wasmtime's default allocator. This bug also requires the memory64 WebAssembly feature to be enabled, which is on-by-default.

Panicking in the host process is considered a denial-of-service vector for Wasmtime.

Patches

Wasmtime 36.0.8, 43.0.2, and 44.0.1 have all been released which fixes this issue.

Workarounds

Embeddings can switch to using the pooling allocator to work around this issue, or the memory64 WebAssembly proposal can be disabled. Otherwise there is no workaround and users are recommended to upgrade.

EPSS Score: 0.00049 (0.154)

Common Weakness Enumeration (CWE)

ADVISORY - nist

Allocation of Resources Without Limits or Throttling

ADVISORY - github

Allocation of Resources Without Limits or Throttling

ADVISORY - redhat

Integer Overflow or Wraparound


GitHub

CREATED

UPDATED

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

5.9medium
PackageTypeOS NameOS VersionAffected RangesFix Versions
wasmtimecargo-->=37.0.0,<43.0.243.0.2
wasmtimecargo-->=30.0.0,<36.0.836.0.8

CVSS:4 Severity and metrics

The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.

The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).

The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.

Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker's payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system. Examples include: utilizing a website that has been modified to display malicious content when the page is rendered (most stored XSS or CSRF) running an application that calls a malicious binary that has been planted on the system using an application which generates traffic over an untrusted or compromised network (vulnerabilities requiring an on-path attacker).

There is no loss of confidentiality within the Vulnerable System.

There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.

There is no loss of integrity within the Vulnerable System.

There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

NIST

CREATED

UPDATED

EXPLOITABILITY SCORE

3.9

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

5.9medium

Debian

CREATED

UPDATED

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

Ubuntu

CREATED

UPDATED

EXPLOITABILITY SCORE

3.9

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-

CVSS SCORE

7.5medium

Red Hat

CREATED

UPDATED

EXPLOITABILITY SCORE

3.9

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

7.5high

Chainguard

CREATED

UPDATED

ADVISORY ID

CGA-4w3c-qcxm-v5gj

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY