dbcve.org
HermesApplication · Facebook

CVE-2021-24044

CRITICAL · 9.8 CVSS v3.1 Published 2022-01-15
Fix available
A fix is available. Upgrade to 0.10.0 or later.
See remediation →
100/100
Remediation priority · Urgent
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
By passing invalid javascript code where await and yield were called upon non-async and non-generator getter/setter functions, Hermes would invoke generator functions and error out on invalid await/yield positions. This could result in segmentation fault as a consequence of type confusion error, with a low chance of RCE. This issue affects Hermes versions prior to v0.10.0.

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

A type confusion vulnerability in the Hermes JavaScript engine allows attackers to cause a segmentation fault by passing invalid JavaScript code that uses await or yield on non-async and non-generator getter/setter functions. Hermes incorrectly invokes generator functions on invalid await/yield positions, leading to type confusion that can potentially result in remote code execution with low probability.

MitigationUpgrade Hermes to version v0.10.0 or later. Until the upgrade is applied, avoid executing untrusted JavaScript code through Hermes and implement input validation on any user-controlled scripts.

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
HermesApplication
Affected:< 0.10.0

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
High
Availability
High

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

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. Identify Hermes version
    Locate the Hermes library binary or package in your deployment and check its version string (e.g., 'hermes --version', check library file metadata, or inspect the version field in your package manager if Hermes is installed as a dependency)
    Affected if The installed Hermes version is below 0.10.0
  2. Confirm Hermes is used for JS execution
    Review your application code and configuration to determine if Hermes is the JavaScript engine responsible for executing JavaScript code in your environment
    Affected if Hermes is actively used as the JavaScript runtime
  3. Determine if untrusted code is processed
    Audit the code paths where Hermes executes JavaScript: identify whether user-supplied or third-party scripts are passed to Hermes without validation, check if Hermes is used in a context where external parties can provide JavaScript input
    Affected if Untrusted or user-controlled JavaScript code is executed through Hermes without sanitization
  4. Inspect for vulnerable await/yield patterns
    Search your JavaScript codebase (or the scripts you run via Hermes) for getter or setter definitions that use 'await' or 'yield' on non-async functions or non-generator functions, which would trigger the type confusion
    Affected if Your scripts contain getter/setter functions that misuse await or yield in ways that trigger the vulnerability

You are affected if your environment runs Hermes version below 0.10.0 and executes untrusted JavaScript code that could contain the specific await/yield on non-async/non-generator getter/setter patterns that trigger the type confusion.

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 0.10.0 or later
Fixed in 0.10.0
Interim mitigation

Upgrade Hermes to version v0.10.0 or later. Until the upgrade is applied, avoid executing untrusted JavaScript code through Hermes and implement input validation on any user-controlled scripts.

Recommended fix High confidence

Hermes v0.10.0

  1. Identify the current Hermes version used in your project (check package.json, podfile, or dependency lock files)
  2. Update the Hermes dependency to version 0.10.0 or later. For React Native projects, update the React Native version that bundles the fixed Hermes version, or explicitly update the Hermes CocoaPod if your project allows it
  3. Rebuild and recompile the application to ensure the new Hermes library is linked
  4. Test the application thoroughly, specifically testing any JavaScript code involving async functions, generators, or custom getters/setters to verify the type confusion vulnerability is resolved
  5. Verify the upgrade by confirming the Hermes version in the built application matches 0.10.0 or later
Caveat Minimal risk - this is a security patch upgrade; however, as with any engine upgrade, perform regression testing on JavaScript execution

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

Fix this in Hermes Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,340
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,144.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-24044 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2021-24044 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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