# CVE-2026-23736: seroval prototype pollution via JSON deserialization

Source: https://junglewise.ai/threats/cve-2026-23736-seroval-prototype-pollution-via-json-deserialization  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-01-21. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-23736 · Severity: low · CVSS 3.1 · Published 2026-01-21

seroval is a JavaScript serialization/deserialization library used for data exchange in web and Node.js applications. A flaw in its JSON deserialization function allows an attacker to inject malicious object keys that pollute the prototype chain, potentially allowing them to modify the behavior of all objects in an application or access sensitive data.

Technologies: [seroval (npm)](https://junglewise.ai/threats/technologies/seroval). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-23736 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-23736 being exploited in the wild.

**How severe is CVE-2026-23736?** Low severity, with a CVSS score of 3.1, published 21 January 2026.

**Which products and versions are affected?** seroval (npm) SEMVER:introduced=0,fixed=1.4.1.

**Is there a fix for CVE-2026-23736?** Yes. seroval (npm): upgrade to 1.4.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-23736 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-23736?** Check whether you run seroval (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- seroval (npm): upgrade to 1.4.1 or later

  ```sh
  npm install seroval@1.4.1
  ```


## Technical details

The vulnerability is a prototype pollution flaw (CWE-1321) triggered during JSON deserialization due to improper input validation of object keys. An attacker can craft a malicious JSON payload with specially crafted keys to pollute the JavaScript prototype chain. The attack requires no authentication or user interaction and is remotely exploitable over the network. Successful exploitation can lead to data disclosure, data manipulation, or denial of service. The vulnerability affects all versions up to 1.4.0; patched in version 1.4.1 and later.

## Affected products

- lxsmnsyc seroval all versions up to and including 1.4.0

## Identifiers

- CVE-2026-23736
- GHSA-hj76-42vx-jwp4

## Timeline

- 2026-01-21: disclosed
- 2026-01-21: patched: Version 1.4.1 and later contain the fix

## References

- [https://github.com/lxsmnsyc/seroval/security/advisories/GHSA-hj76-42vx-jwp4](https://github.com/lxsmnsyc/seroval/security/advisories/GHSA-hj76-42vx-jwp4)

## Related threats

- [Seroval denial of service via array-like object in deserialization](https://junglewise.ai/threats/cve-2026-116584-seroval-facilitates-javascript-value-stringification-including)
- [Seroval typed array constructor name injection](https://junglewise.ai/threats/cve-2026-116583-seroval-facilitates-javascript-value-stringification-including)
- [Seroval JavaScript RegExp code injection in HTML script elements](https://junglewise.ai/threats/cve-2026-116582-seroval-facilitates-javascript-value-stringification-including)
- [Seroval improper sequence node validation in deserialization](https://junglewise.ai/threats/cve-2026-116581-seroval-facilitates-javascript-value-stringification-including)
- [Seroval incomplete fix for AsyncIterator deserialization bypass](https://junglewise.ai/threats/cve-2026-116580-seroval-facilitates-javascript-value-stringification-including)