Bytecode Alliance Wasmtime up to 36.0.16/48.0.3/49.0.1 Wasi write-zeroes allocation of resources

Summaryinfo

A vulnerability identified as problematic has been detected in Bytecode Alliance Wasmtime up to 36.0.16/48.0.3/49.0.1. This affects the function write-zeroes of the component Wasi. Performing a manipulation results in allocation of resources. This vulnerability is reported as CVE-2026-115381. The attack is possible to be carried out remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Bytecode Alliance Wasmtime up to 36.0.16/48.0.3/49.0.1. It has been classified as problematic. This affects the function write-zeroes of the component Wasi. The manipulation with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. This is going to have an impact on availability. The summary by CVE is:

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an unbounded memory allocation in the wasmtime-wasi WASIp2 write-zeroes method of SinkOutputStream, the default stream used when stdout/stderr are not configured. A malicious WebAssembly guest can request huge zero-filled writes, exhausting host memory and causing denial of service.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-115381 since 10/22/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 36.0.17, 48.0.4 or 49.0.2 eliminates this vulnerability.

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Productinfo

Vendor

• Bytecode Alliance

Name

• Wasmtime

Version

• 36.0.0
• 36.0.1
• 36.0.2
• 36.0.3
• 36.0.4
• 36.0.5
• 36.0.6
• 36.0.7
• 36.0.8
• 36.0.9
• 36.0.10
• 36.0.11
• 36.0.12
• 36.0.13
• 36.0.14
• 36.0.15
• 36.0.16
• 48.0.0
• 48.0.1
• 48.0.2
• 48.0.3
• 49.0.0
• 49.0.1

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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