Vulnerability · Published Oct 22, 2026 · Assigned by VulnCheck

CVE-2026-115388Wasmtime 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

Medium 6.2

In plain English

A medium-severity uncontrolled resource consumption in wasmtime from bytecodealliance. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities).

Severity (CVSS 3.1)6.2Medium

Exploit odds (30 days)0.1%top 98.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Ubuntu:24.04:LTS	rust-wasmtime	no fix listed	UBUNTU-CVE-2026-115388
Ubuntu:26.04:LTS	rust-wasmtime	no fix listed	UBUNTU-CVE-2026-115388
Ubuntu:26.10	rust-wasmtime	no fix listed	UBUNTU-CVE-2026-115388

Affected products (as reported)

Vendor	Product	Versions
bytecodealliance	wasmtime	0 – before 36.0.1637.0.0 – before 48.0.349.0.0 – before 49.0.1

Weakness: CWE-400 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

GitHub Security Advisory (GHSA-c9gc-w9vx-w86p) vendor-advisory
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 third-party-advisory