CVE-2026-85238: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-q8j2-7wc6-q8m4
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CVSS 6.8
CWE-384
Published
Advisory Summary

CVE-2026-85238 is a HIGH (CVSS 6.8) security vulnerability vulnerability (CWE-384: Session Fixation) affecting Software libraries in the Maven ecosystem. The weakness occurs when authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-85238 at a Glance

CVE Identifier CVE-2026-85238
GHSA Identifier GHSA-q8j2-7wc6-q8m4
Severity HIGH
CVSS v3.1 Base Score 6.8
CWE Classification CWE-384: Session Fixation
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.8

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:N).

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 None (A:N)

How to Fix CVE-2026-85238

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-2026-85238, 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-384: Session Fixation, where authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions. 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

MISP contains a session fixation vulnerability in the CustomAuth authentication (a custom configuration) flow. When a user was successfully authenticated through CustomAuth, MISP stored the authenticated user identity in the existing session without first rotating the session identifier. As a result, if an attacker can cause a victim to use a session identifier known to the attacker before authentication, that same session identifier remains valid after the victim successfully authenticates. The attacker could subsequently reuse the fixed session identifier to access the victim's authenticated MISP session, potentially gaining the privileges associated with the victim's account. The issue occurs because __customAuthentication() wrote the authenticated user into the existing CakePHP session while the call to Session->renew() had previously been disabled. The patch restores session identifier rotation when a new authentication occurs or when the authenticated user changes, while avoiding unnecessary session renewal on every request.

References

NVD — CVE-2026-85238 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-85238
Security Fix Commit FIX COMMIT
https://github.com/MISP/MISP/commit/e2eb2f058

Frequently Asked Questions

What is CVE-2026-85238?
CVE-2026-85238 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-384: Session Fixation.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-85238?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-85238?
CVE-2026-85238 has a CVSS v3.1 base score of 6.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-85238?
CVE-2026-85238 is classified under CWE-384: Session Fixation (Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.).
How can I check Maven dependencies for CVE-2026-85238?
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-q8j2-7wc6-q8m4",
  "modified" : "2026-09-11T15:32:26Z",
  "published" : "2026-09-03T18:31:47Z",
  "aliases" : [ "CVE-2026-85238" ],
  "details" : "MISP contains a session fixation vulnerability in the CustomAuth authentication (a custom configuration) flow. When a user was successfully authenticated through CustomAuth, MISP stored the authenticated user identity in the existing session without first rotating the session identifier.\n\n\nAs a result, if an attacker can cause a victim to use a session identifier known to the attacker before authentication, that same session identifier remains valid after the victim successfully authenticates. The attacker could subsequently reuse the fixed session identifier to access the victim's authenticated MISP session, potentially gaining the privileges associated with the victim's account.\n\n\nThe issue occurs because __customAuthentication() wrote the authenticated user into the existing CakePHP session while the call to Session->renew() had previously been disabled. The patch restores session identifier rotation when a new authentication occurs or when the authenticated user changes, while avoiding unnecessary session renewal on every request.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/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" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-85238"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/MISP/MISP/commit/e2eb2f058"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-384" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-03T16:18:27Z"
  }
}