CVE-2023-23557
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 · uneditedAn error in Hermes' algorithm for copying objects properties prior to commit a00d237346894c6067a594983be6634f4168c9ad could be used by a malicious attacker to execute arbitrary code via type confusion. Note that this is only exploitable in cases where Hermes is used to execute 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 analysisA resource is accessed as one type when it was actually allocated as another, so the code misreads memory layout — in interpreters and language runtimes this is frequently a direct path to code execution. It often arises from unchecked casts on attacker-influenced objects. The fix is strict type checks before casts and memory-safe access patterns.
General guidance for the type confusion class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
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< 2023-01-10CVSS 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 · scoped2023-01-10
Hermes version 0.12.0 or later (any stable release after 2023-01-10)
- 1. Identify the current Hermes version in your project by checking package.json or your dependency lock file
- 2. Upgrade the Hermes dependency to a version released after January 10, 2023 (e.g., Hermes v0.12.0 or later)
- 3. Run `npm install` or `yarn install` to update the dependency
- 4. Rebuild your React Native application to include the updated Hermes engine
- 5. Verify the upgrade was successful by checking that Hermes version is >= the version containing commit a00d237346894c6067a594983be6634f4168c9ad
Generated from the published advisory — verify against the referenced sources before acting.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-23557 — 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 sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-23557 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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