What’s Vulnerable › Vulnerabilities

CVE-2026-115388: Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Memory Exhaustion DoS via wasmtime-wasi-http Outgoing Body Write

• Severity: medium (CVSS 6.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% 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-400

Description

wasmtime-wasi-http in Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not enforce the wasi:io/streams check-write allowance for WASIp2 outgoing HTTP bodies, so oversized writes succeed instead of trapping. A malicious guest can pass large buffers to write on outgoing-body resources, holding host allocations for the store's lifetime and exhausting host memory.

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-c9gc-w9vx-w86p
• 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-memory-exhaustion-dos-via-wasmtime-wasi-http-outgoing-body-write

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