---
id: CVE-2026-115388
title: >-
  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
summary: >-
  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 …
severity: medium
cvss: 6.2
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-400
vendor: bytecodealliance
product: wasmtime
affected:
  - wasmtime < 36.0.16
  - wasmtime >= 37.0.0 < 48.0.3
  - wasmtime >= 49.0.0 < 49.0.1
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-29T02:31:12.064625Z'
published: '2026-10-22'
updated: '2026-10-29'
sourceUpdated: '2026-10-29T02:31:21.887Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-115388'
references:
  - url: >-
      https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-c9gc-w9vx-w86p
    label: GitHub Security Advisory (GHSA-c9gc-w9vx-w86p)
  - url: >-
      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
    label: >-
      VulnCheck Advisory: 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
  - url: 'https://crates.io/crates/wasmtime-wasi-http'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0313.html'
  - url: 'https://github.com/bytecodealliance/wasmtime/pull/14408'
tags:
  - cve.org
  - osv
  - rust
epss: 0.00112
epssPercentile: 0.01374
aliases:
  - RUSTSEC-2026-0313
  - GHSA-c9gc-w9vx-w86p
ecosystem: rust
patched:
  - wasmtime-wasi-http 49.0.1
ingestedAt: '2026-10-22T22:00:50.404Z'
---

## Overview

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

- `wasmtime < 36.0.16`
- `wasmtime >= 37.0.0 < 48.0.3`
- `wasmtime >= 49.0.0 < 49.0.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-115388)

Affected packages:

- `wasmtime-wasi-http >= 49.0.0, < 49.0.1`

Patched in:

- `wasmtime-wasi-http 49.0.1`

Source: https://osv.dev/vulnerability/RUSTSEC-2026-0313