CVE-2026-41161: @sync in/server Sync-in Server Has Username Enumeration Vulnerability

MODERATE
Advisory Identifier: GHSA-43fj-qp3h-hrh5
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CWE-208
Published
Advisory Summary

CVE-2026-41161 is a MODERATE sync-in server has username enumeration vulnerability (CWE-208: Observable Timing Discrepancy) affecting @sync in/server libraries in the npm ecosystem. The issue involves sync-in server has username enumeration via timing attack. Remediation is available by upgrading affected packages to version 2.2.0.

CVE-2026-41161 at a Glance

CVE Identifier CVE-2026-41161
GHSA Identifier GHSA-43fj-qp3h-hrh5
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-208: Observable Timing Discrepancy
Affected Product @sync in/server
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-41161

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

@sync-in/server fixed: 2.2.0 
npm install @sync-in/server@2.2.0
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 @sync-in/server

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-41161, inspect your project dependencies using npm:

npm ls @sync-in/server

Analyze the terminal output to locate any version of @sync in/server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.2.0), your application is affected.

Note: The npm ls @sync-in/server 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-208: Observable Timing Discrepancy, where two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not. In @sync in/server, 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

### Summary The `/api/auth/login` endpoint contains a logic flaw that allows unauthenticated remote attackers to enumerate valid usernames by measuring the application's response time. ### Details The logic flaw can be located at the below point in source: https://github.com/Sync-in/server/blob/7868bb2b3025f92e6c38087456304758713971b2/backend/src/applications/users/services/users-queries.service.ts#L91-L95 Endpoints used for authentication should respond to the user with a consistent cadence, preventing remote actors from deriving sensitive information about an application based on backend behavior. In the case of authentication endpoints, this timing discrepancy is often caused by short-circuiting due to the lack of a matched user to compare against - as is the case with Sync-in. ### Validation TickTock Enum (Burp Suite Extension) was utilized to validate this finding. Authentication attempts with a valid username see a response from the application at around 350-400ms on average, while invalid usernames are returned at only 95-100ms on average. <img width="1302" height="284" alt="image" src="https://github.com/user-attachments/assets/31eeb72a-c3c2-4057-ac69-c0c92f0bbd4e" /> ### Impact An unauthenticated remote attacker can enumerate valid usernames. This significantly weakens the application's security posture by facilitating targeted brute-force attacks, stuffing, social engineering, and a suite of other more targeted attacks.

CVE-2026-41161 Affected @sync in/server Versions

1 component(s)
Fixed Versions:
2.2.0
Product / Package Ecosystem Affected Versions Fixed Version
@sync-in/server
npm/@sync-in/server
npm
< 2.2.0
2.2.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/Sync-in/server/security/advisories/GHSA-43fj-qp3h-hrh5
NVD — CVE-2026-41161 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-41161
@sync in/server Source Repository REPOSITORY
https://github.com/Sync-in/server
@sync in/server Release RELEASE
https://github.com/Sync-in/server/releases/tag/v2.2.0

Frequently Asked Questions

What is CVE-2026-41161?
CVE-2026-41161 is a security vulnerability in @sync in/server involving Sync-in Server has Username Enumeration via Timing Attack under CWE-208: Observable Timing Discrepancy.
Which @sync in/server versions are affected?
Affected versions include releases prior to 2.2.0 across affected packages: @sync-in/server.
What version fixes CVE-2026-41161?
Upgrading to 2.2.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @sync-in/server affected?
Yes, @sync-in/server is affected in releases prior to 2.2.0. Upgrade your dependency to 2.2.0 or later.
What CWE is associated with CVE-2026-41161?
CVE-2026-41161 is classified under CWE-208: Observable Timing Discrepancy (Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.).
How can I check npm dependencies for CVE-2026-41161?
Run the dependency tree command: 'npm ls @sync-in/server'. 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-43fj-qp3h-hrh5",
  "modified" : "2026-05-12T13:31:20Z",
  "published" : "2026-04-15T18:57:50Z",
  "aliases" : [ "CVE-2026-41161" ],
  "summary" : "Sync-in Server has Username Enumeration via Timing Attack",
  "details" : "### Summary\nThe `/api/auth/login` endpoint contains a logic flaw that allows unauthenticated remote attackers to enumerate valid usernames by measuring the application's response time.\n\n### Details\nThe logic flaw can be located at the below point in source:\nhttps://github.com/Sync-in/server/blob/7868bb2b3025f92e6c38087456304758713971b2/backend/src/applications/users/services/users-queries.service.ts#L91-L95\n\nEndpoints used for authentication should respond to the user with a consistent cadence, preventing remote actors from deriving sensitive information about an application based on backend behavior. In the case of authentication endpoints, this timing discrepancy is often caused by short-circuiting due to the lack of a matched user to compare against - as is the case with Sync-in.\n\n### Validation\nTickTock Enum (Burp Suite Extension) was utilized to validate this finding. Authentication attempts with a valid username see a response from the application at around 350-400ms on average, while invalid usernames are returned at only 95-100ms on average.\n<img width=\"1302\" height=\"284\" alt=\"image\" src=\"https://github.com/user-attachments/assets/31eeb72a-c3c2-4057-ac69-c0c92f0bbd4e\" />\n\n### Impact\nAn unauthenticated remote attacker can enumerate valid usernames. This significantly weakens the application's security posture by facilitating targeted brute-force attacks, stuffing, social engineering, and a suite of other more targeted attacks.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@sync-in/server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.2.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.1.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/Sync-in/server/security/advisories/GHSA-43fj-qp3h-hrh5"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-41161"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Sync-in/server"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Sync-in/server/releases/tag/v2.2.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-208" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-15T18:57:50Z",
    "nvd_published_at" : "2026-05-08T14:16:33Z"
  }
}