GHSA-9xwc-vwww-qqmw: Duplicate Advisory Vikunja: Link-share Principal-type Confusion Enables Vulnerability

HIGH
Share
CVSS 7.5
CWE-639
Published
Advisory Summary

GHSA-9xwc-vwww-qqmw is a HIGH (CVSS 7.5) vikunja: link-share principal-type confusion enables vulnerability (CWE-639: Authorization Bypass Through User-Controlled Key) affecting Duplicate Advisory libraries in the Go ecosystem. The issue involves vikunja: link-share principal-type confusion enables cross-account team removal, bot takeover, and roster disclosure. Remediation is available in the latest vendor maintenance releases.

GHSA-9xwc-vwww-qqmw at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-9xwc-vwww-qqmw
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-639: Authorization Bypass Through User-Controlled Key
Affected Product Duplicate Advisory
Package Ecosystem Go
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:H/PR:L/UI:N/S:U/C:H/I:H/A:H).

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

How to Fix GHSA-9xwc-vwww-qqmw

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

code.vikunja.io/api fixed: Latest secure release 
Upgrade code.vikunja.io/api to Latest secure release
Verify Direct and Transitive Dependencies

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

inspect dependencies for code.vikunja.io/api

How to Check if You Are Affected

To determine whether your application is affected by GHSA-9xwc-vwww-qqmw, inspect your project dependencies for Duplicate Advisory:

inspect dependencies for code.vikunja.io/api

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

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-639: Authorization Bypass Through User-Controlled Key, where the system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. In Duplicate Advisory, 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

### Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-32r8-5843-4qw2. This link is maintained to preserve external references. ### Original Description Vikunja through 2.4.0 contains a principal-type confusion vulnerability where LinkSharing principals with id N are treated as user principals with users.id == N at three permission checks lacking type guards. Attackers with a link-share JWT can remove victims from teams, enumerate and delete victim bot users, or read team rosters by exploiting id collisions in the autoincrement space.

GHSA-9xwc-vwww-qqmw Affected Duplicate Advisory Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
code.vikunja.io/api
golang/code.vikunja.io/api
Go
≤ 2.4.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-32r8-5843-4qw2
NVD — GHSA-9xwc-vwww-qqmw NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-76216
www.vulncheck.com/advisories/vikunja-... WEB
https://www.vulncheck.com/advisories/vikunja-through-principal-type-confusion-via-linksharing

Frequently Asked Questions

What is GHSA-9xwc-vwww-qqmw?
GHSA-9xwc-vwww-qqmw is a security vulnerability in Duplicate Advisory involving Vikunja: Link-share principal-type confusion enables cross-account team removal, bot takeover, and roster disclosure under CWE-639: Authorization Bypass Through User-Controlled Key.
Which Duplicate Advisory versions are affected?
Affected versions include releases prior to current release patches across affected packages: code.vikunja.io/api.
What version fixes GHSA-9xwc-vwww-qqmw?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is code.vikunja.io/api affected?
Yes, code.vikunja.io/api is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of GHSA-9xwc-vwww-qqmw?
GHSA-9xwc-vwww-qqmw has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with GHSA-9xwc-vwww-qqmw?
GHSA-9xwc-vwww-qqmw is classified under CWE-639: Authorization Bypass Through User-Controlled Key (The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.).
How can I check Go dependencies for GHSA-9xwc-vwww-qqmw?
Run the dependency tree command: 'inspect dependencies for code.vikunja.io/api'. 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-9xwc-vwww-qqmw",
  "modified" : "2026-10-09T20:43:21Z",
  "published" : "2026-08-19T15:32:33Z",
  "withdrawn" : "2026-10-09T20:43:21Z",
  "aliases" : [ ],
  "summary" : "Duplicate Advisory: Vikunja: Link-share principal-type confusion enables cross-account team removal, bot takeover, and roster disclosure",
  "details" : "### Duplicate Advisory\nThis advisory has been withdrawn because it is a duplicate of GHSA-32r8-5843-4qw2. This link is maintained to preserve external references.\n\n### Original Description\nVikunja through 2.4.0 contains a principal-type confusion vulnerability where LinkSharing principals with id N are treated as user principals with users.id == N at three permission checks lacking type guards. Attackers with a link-share JWT can remove victims from teams, enumerate and delete victim bot users, or read team rosters by exploiting id collisions in the autoincrement space.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "code.vikunja.io/api"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "2.4.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-32r8-5843-4qw2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-76216"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/vikunja-through-principal-type-confusion-via-linksharing"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-09T20:43:21Z",
    "nvd_published_at" : "2026-08-19T14:17:47Z"
  }
}