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CVE-2026-104855

Vulnerability in wasmtime (CVE-2026-104855)

Summary

Vulnerability in wasmtime (CVE-2026-104855). Risk of unauthorized operations or information disclosure. Exploitable via memory.copy. Mitigation: upgrade to 47.0.3 or later.

Original description

The description as published by the source.

This is an entry in the RustSec database for the Wasmtime security advisory
located at
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2hw9-mc66-jc2q
For more information see the GitHub-hosted security advisory.

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-104855 has been found in wasmtime.
Attackers can target a specific entry point like memory.copy over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade wasmtime to 47.0.3 or later.
If unsure, ask your IT team or search "wasmtime CVE-2026-104855" on the vendor's site.

CVE-2026-104855 (wasmtime) — CWE-362
Attack surface: memory.copy / array.copy / Store / table.grow
Patched: 47.0.3 — apply immediately
Workaround: Embedders using Store::epoch_deadline_callback are safe if they only access the T in Store<T>.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-362) exists in wasmtime. Attackers reach the vulnerable code path via memory.copy.

📍 Affected scope

Check the vendor advisory for the affected versions of wasmtime. Attack surface: memory.copy / array.copy / Store / table.grow.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 47.0.3.

🛡️ Workaround

Workaround: Embedders using Store::epoch_deadline_callback are safe if they only access the T in Store<T>.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'wasmtime' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'wasmtime' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で wasmtime を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply temporary workaround mitigate 
    Embedders using `Store::epoch_deadline_callback` are safe if they only access the `T` in `Store<T>`.

    パッチが適用されるまでの応急処置として、Embedders using Store::epoch_deadline_callback are safe if they only access the T in Store<T>. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade wasmtime to 47.0.3

    ステージング環境で 47.0.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  4. 4
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

rust wasmtime
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"47.0.3"}]}]
crates.io wasmtime
[{"type":"SEMVER","events":[{"introduced":"46.0.0"},{"fixed":"46.0.2"},{"introduced":"47.0.0"},{"fixed":"47.0.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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