CVE-2026-23956: Seroval Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-hx9m-jf43-8ffr
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CVSS 7.5
CWE-1333
Published
Advisory Summary

CVE-2026-23956 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-1333: Inefficient Regular Expression Complexity) affecting Seroval libraries in the npm ecosystem. The issue involves seroval affected by denial of service via regexp serialization. Remediation is available by upgrading affected packages to version 1.4.1.

CVE-2026-23956 at a Glance

CVE Identifier CVE-2026-23956
GHSA Identifier GHSA-hx9m-jf43-8ffr
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-1333: Inefficient Regular Expression Complexity
Affected Product Seroval
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-23956

To remediate this vulnerability, upgrade all affected Seroval dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

seroval fixed: 1.4.1 
npm install seroval@1.4.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls seroval

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-23956, inspect your project dependencies using npm:

npm ls seroval

Analyze the terminal output to locate any version of Seroval in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.4.1), your application is affected.

Note: The npm ls seroval command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1333: Inefficient Regular Expression Complexity, where the product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential. In Seroval, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Overriding RegExp serialization with extremely large patterns can **exhaust JavaScript runtime memory** during deserialization. Additionally, overriding RegExp serialization with patterns that trigger **catastrophic backtracking** can lead to ReDoS (Regular Expression Denial of Service). **Mitigation**: `Seroval` introduces `disabledFeatures` (a bitmask) in serialization/deserialization methods, with `Feature.RegExp` as a dedicated flag. **Users are recommended to configure `disabledFeatures` to disable RegExp serialization entirely.**

CVE-2026-23956 Affected Seroval Versions

1 component(s)
Fixed Versions:
1.4.1
Product / Package Ecosystem Affected Versions Fixed Version
seroval
npm/seroval
npm
≥ 0.2.0
< 1.4.1
1.4.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/lxsmnsyc/seroval/security/advisories/GHSA-hx9m-jf43-8ffr
NVD — CVE-2026-23956 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-23956
Security Fix Commit FIX COMMIT
https://github.com/lxsmnsyc/seroval/commit/ce9408ebc87312fcad345a73c172212f2a798060
Seroval Source Repository REPOSITORY
https://github.com/lxsmnsyc/seroval
Seroval Source Repository REPOSITORY
https://github.com/lxsmnsyc/seroval/blob/v0.2.0/packages/seroval/src/index.ts#L90

Frequently Asked Questions

What is CVE-2026-23956?
CVE-2026-23956 is a security vulnerability in Seroval involving seroval affected by Denial of Service via RegExp serialization under CWE-1333: Inefficient Regular Expression Complexity.
Which Seroval versions are affected?
Affected versions include releases prior to 1.4.1 across affected packages: seroval.
What version fixes CVE-2026-23956?
Upgrading to 1.4.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is seroval affected?
Yes, seroval is affected in releases prior to 1.4.1. Upgrade your dependency to 1.4.1 or later.
What is the CVSS score of CVE-2026-23956?
CVE-2026-23956 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-23956?
CVE-2026-23956 is classified under CWE-1333: Inefficient Regular Expression Complexity (The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.).
How can I check npm dependencies for CVE-2026-23956?
Run the dependency tree command: 'npm ls seroval'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hx9m-jf43-8ffr",
  "modified" : "2026-05-20T00:53:27Z",
  "published" : "2026-01-21T16:57:06Z",
  "aliases" : [ "CVE-2026-23956" ],
  "summary" : "seroval affected by Denial of Service via RegExp serialization",
  "details" : "Overriding RegExp serialization with extremely large patterns can **exhaust JavaScript runtime memory** during deserialization. Additionally, overriding RegExp serialization with patterns that trigger **catastrophic backtracking** can lead to ReDoS (Regular Expression Denial of Service).  \n\n**Mitigation**:  \n`Seroval` introduces `disabledFeatures` (a bitmask) in serialization/deserialization methods, with `Feature.RegExp` as a dedicated flag. **Users are recommended to configure `disabledFeatures` to disable RegExp serialization entirely.**",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "seroval"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.2.0"
      }, {
        "fixed" : "1.4.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.4.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/lxsmnsyc/seroval/security/advisories/GHSA-hx9m-jf43-8ffr"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-23956"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/lxsmnsyc/seroval/commit/ce9408ebc87312fcad345a73c172212f2a798060"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/lxsmnsyc/seroval"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/lxsmnsyc/seroval/blob/v0.2.0/packages/seroval/src/index.ts#L90"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1333" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-21T16:57:06Z",
    "nvd_published_at" : "2026-01-22T02:15:52Z"
  }
}