dbcve.org
Js ComputeApplication · Fastly

CVE-2022-39218

HIGH · 7.5 CVSS v3.1 Published 2022-09-20
Fix available
A fix is available. Upgrade to 0.5.3 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The JS Compute Runtime for Fastly's Compute@Edge platform provides the environment JavaScript is executed in when using the Compute@Edge JavaScript SDK. In versions prior to 0.5.3, the `Math.random` and `crypto.getRandomValues` methods fail to use sufficiently random values. The initial value to seed the PRNG (pseudorandom number generator) is baked-in to the final WebAssembly module, making the sequence of random values for that specific WebAssembly module predictable. An attacker can use the fixed seed to predict random numbers generated by these functions and bypass cryptographic security controls, for example to disclose sensitive data encrypted by functions that use these generators. The problem has been patched in version 0.5.3. No known workarounds exist.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The JS Compute Runtime for Fastly's Compute@Edge embeds a static seed in the compiled WebAssembly module for Math.random and crypto.getRandomValues, making the PRNG sequence predictable. Attackers can exploit this to predict random values and bypass cryptographic security controls protecting sensitive data.

MitigationUpgrade to version 0.5.3 or later of the Compute@Edge JavaScript SDK to obtain properly randomized seeding. No workarounds exist; immediate patching is required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Js ComputeApplication
Affected:< 0.5.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Fastly JS Compute SDK version
    Examine your project's package.json or package-lock.json file for the @fastly/js-compute dependency version. Run 'npm list @fastly/js-compute' or 'yarn list @fastly/js-compute' to see the installed version.
    Affected if The installed version is lower than 0.5.3 (e.g., 0.5.2, 0.5.1, 0.5.0, or any 0.x version below 0.5.3).
  2. Identify Math.random usage
    Search your source code for calls to Math.random(). Use grep, grep -r 'Math.random' ., or your IDE's search function across all .js files in your compute project.
    Affected if Your code contains Math.random() calls and the SDK version is below 0.5.3.
  3. Identify crypto.getRandomValues usage
    Search your source code for calls to crypto.getRandomValues(). Use grep, grep -r 'getRandomValues' ., or your IDE's search function across all .js files in your compute project.
    Affected if Your code contains crypto.getRandomValues() calls and the SDK version is below 0.5.3.
  4. Verify the compiled WebAssembly module
    Locate the compiled .wasm file in your build output (typically in the dist/ or output/ directory). Inspect the binary for the static seed pattern used by the vulnerable version, or check the build logs for the SDK version used during compilation.
    Affected if The .wasm binary was compiled with a JS Compute SDK version below 0.5.3 and the application uses Math.random or crypto.getRandomValues.

You are affected if your project uses Fastly JS Compute SDK version below 0.5.3 AND your code calls Math.random() or crypto.getRandomValues, as the compiled WebAssembly module contains a predictable static seed.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 0.5.3 or later
Fixed in 0.5.3
Interim mitigation

Upgrade to version 0.5.3 or later of the Compute@Edge JavaScript SDK to obtain properly randomized seeding. No workarounds exist; immediate patching is required.

Recommended fix High confidence

Js Compute 0.5.3 or later

  1. Check the current Js Compute version in your project (e.g., in package.json or dependency lock file)
  2. Update Js Compute dependency to version 0.5.3 or later using your package manager (e.g., npm update @fastly/js-compute)
  3. Rebuild your Compute@Edge WebAssembly module with the updated runtime
  4. Redeploy the updated WebAssembly module to your Fastly Compute@Edge service
  5. Verify the application functions correctly with the new version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Js Compute Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-39218 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data