HermesApplication · Facebook

CVE-2020-1914

CRITICAL · 9.8 CVSS v3.1 Published 2020-10-08
Fix available
A fix is available. Upgrade to 2020-10-01 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

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
A logic vulnerability when handling the SaveGeneratorLong instruction in Facebook Hermes prior to commit b2021df620824627f5a8c96615edbd1eb7fdddfc allows attackers to potentially read out of bounds or theoretically execute arbitrary code via crafted JavaScript. Note that this is only exploitable if the application using Hermes permits evaluation of untrusted JavaScript. Hence, most React Native applications are not affected.

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

A detailed technical summary for this CVE is being prepared.

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:< 2020-10-01

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

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 2020-10-01 or later
Fixed in 2020-10-01
Vendor patch github.com →
Recommended fix High confidence

Hermes version from October 2020 or later (any release after the 2020-10-01 cutoff)

  1. 1. Identify the current version of Hermes used in your application by checking your package.json or the hermes-engine dependency
  2. 2. If your Hermes version is older than the October 2020 release, upgrade to a newer version of the @react-native-community/hermes-engine package (or react-native-hermes depending on your setup)
  3. 3. Run npm install or yarn to fetch the updated Hermes engine
  4. 4. Rebuild your React Native application to ensure the new Hermes engine is bundled
  5. 5. Test your application thoroughly, especially any JavaScript evaluation features, to verify functionality is intact
  6. 6. If you are using a React Native version, ensure it bundles a Hermes version from October 2020 or later
Caveat Minimal risk; Hermes is generally backward compatible. However, test thoroughly as with any security update

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $2,300. Get the upgrade done

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2020-1914 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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-2020-1914 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