What’s Vulnerable › Vulnerabilities

CVE-2026-115389: Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Denial of Service via Val API

• Severity: low (CVSS 2.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-22 · updated 2026-10-29
• Weakness: CWE-770

Description

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Affected products

• bytecodealliance wasmtime: before 36.0.16; from 37.0.0 before 48.0.3; from 49.0.0 before 49.0.1 — fixed in 36.0.16, 48.0.3, 49.0.1

How to fix

Upgrade to a fixed version: bytecodealliance wasmtime 36.0.16, 48.0.3, 49.0.1. Check the vendor advisory for mitigations.

References

• https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jqpg-j7w6-42pr
• https://www.vulncheck.com/advisories/wasmtime-before-36.0.16-37.0.0-before-48.0.3-and-49.0.0-before-49.0.1-denial-of-service-via-val-api

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