CVE-2026-109373: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-ff7c-8692-c559
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CVSS 8.1
CWE-441
Published
Advisory Summary

CVE-2026-109373 is a CRITICAL (CVSS 8.1) security vulnerability vulnerability (CWE-441: Unintended Proxy or Intermediary ('Confused Deputy')) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. this causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-109373 at a Glance

CVE Identifier CVE-2026-109373
GHSA Identifier GHSA-ff7c-8692-c559
Severity CRITICAL
CVSS v3.1 Base Score 8.1
CWE Classification CWE-441: Unintended Proxy or Intermediary ('Confused Deputy')
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.1

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

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

How to Fix CVE-2026-109373

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

Verify Direct and Transitive Dependencies

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

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-109373, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software 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: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-441: Unintended Proxy or Intermediary ('Confused Deputy'), where the product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. this causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor. In Software, 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

ZITADEL 3.0.0 before 4.19.2 contains an authentication bypass vulnerability in the Login V2 UI that allows unauthenticated attackers to obtain other users' session tokens by forging unsigned session cookies. Attackers can guess time-ordered session IDs around a victim's sign-in and supply them with empty tokens to receive rotated tokens, taking over accounts including MFA-completed administrator sessions.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/zitadel/zitadel/security/advisories/GHSA-jh92-5mrj-p2w2
NVD — CVE-2026-109373 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-109373
www.vulncheck.com/advisories/zitadel-... WEB
https://www.vulncheck.com/advisories/zitadel-3.0.0-before-4.19.2-account-takeover-via-unsigned-login-v2-session-cookie

Frequently Asked Questions

What is CVE-2026-109373?
CVE-2026-109373 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-441: Unintended Proxy or Intermediary ('Confused Deputy').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-109373?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-109373?
CVE-2026-109373 has a CVSS v3.1 base score of 8.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-109373?
CVE-2026-109373 is classified under CWE-441: Unintended Proxy or Intermediary ('Confused Deputy') (The product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. This causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor.).
How can I check Maven dependencies for CVE-2026-109373?
Run the dependency tree command: 'mvn dependency:tree'. 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-ff7c-8692-c559",
  "modified" : "2026-10-12T18:31:54Z",
  "published" : "2026-10-12T18:31:54Z",
  "aliases" : [ "CVE-2026-109373" ],
  "details" : "ZITADEL 3.0.0 before 4.19.2 contains an authentication bypass vulnerability in the Login V2 UI that allows unauthenticated attackers to obtain other users' session tokens by forging unsigned session cookies. Attackers can guess time-ordered session IDs around a victim's sign-in and supply them with empty tokens to receive rotated tokens, taking over accounts including MFA-completed administrator sessions.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/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" : [ ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/zitadel/zitadel/security/advisories/GHSA-jh92-5mrj-p2w2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-109373"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/zitadel-3.0.0-before-4.19.2-account-takeover-via-unsigned-login-v2-session-cookie"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-441" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-10-12T17:17:35Z"
  }
}