CVE-2026-7887: Concrete CMS OAuth 2.0 Authorization-Code Handler Bypasses Vulnerability

LOW
Advisory Identifier: GHSA-f54h-78c9-c24h
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CWE-1287
Published
Advisory Summary

CVE-2026-7887 is a LOW oauth 2.0 authorization-code handler bypasses vulnerability (CWE-1287: Improper Validation of Specified Type of Input) affecting Concrete CMS libraries in the Packagist ecosystem. The issue involves oauth 2.0 authorization-code handler bypasses account status. Remediation is available by upgrading affected packages to version 9.5.1.

CVE-2026-7887 at a Glance

CVE Identifier CVE-2026-7887
GHSA Identifier GHSA-f54h-78c9-c24h
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-1287: Improper Validation of Specified Type of Input
Affected Product Concrete CMS
Package Ecosystem Packagist
Published Date
Last Updated

How to Fix CVE-2026-7887

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

concrete5/concrete5 fixed: 9.5.1 
Upgrade concrete5/concrete5 to 9.5.1
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 concrete5/concrete5

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-7887, inspect your project dependencies for Concrete CMS:

inspect dependencies for concrete5/concrete5

Analyze the terminal output to locate any version of Concrete CMS in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.5.1), 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-1287: Improper Validation of Specified Type of Input, where the product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type. In Concrete CMS, 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

For Concrete CMS 9.5.0 and below, OAuth 2.0 Authorization-Code Handler Bypasses Account Status. A user with uIsActive=0 (suspended, banned, terminated employee) can still authenticate via OAuth and receive valid API tokens. 

CVE-2026-7887 Affected Concrete CMS Versions

1 component(s)
Fixed Versions:
9.5.1
Product / Package Ecosystem Affected Versions Fixed Version
concrete5/concrete5
 Packagist
< 9.5.1
9.5.1

References

NVD — CVE-2026-7887 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-7887
Concrete CMS Release RELEASE
https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
Concrete CMS Source Repository REPOSITORY
https://github.com/concretecms/concretecms

Frequently Asked Questions

What is CVE-2026-7887?
CVE-2026-7887 is a security vulnerability in Concrete CMS involving OAuth 2.0 Authorization-Code Handler Bypasses Account Status under CWE-1287: Improper Validation of Specified Type of Input.
Which Concrete CMS versions are affected?
Affected versions include releases prior to 9.5.1 across affected packages: concrete5/concrete5.
What version fixes CVE-2026-7887?
Upgrading to 9.5.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is concrete5/concrete5 affected?
Yes, concrete5/concrete5 is affected in releases prior to 9.5.1. Upgrade your dependency to 9.5.1 or later.
What CWE is associated with CVE-2026-7887?
CVE-2026-7887 is classified under CWE-1287: Improper Validation of Specified Type of Input (The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.).
How can I check Packagist dependencies for CVE-2026-7887?
Run the dependency tree command: 'inspect dependencies for concrete5/concrete5'. 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-f54h-78c9-c24h",
  "modified" : "2026-06-24T21:11:57Z",
  "published" : "2026-05-22T00:31:16Z",
  "aliases" : [ "CVE-2026-7887" ],
  "summary" : "Concrete CMS: OAuth 2.0 Authorization-Code Handler Bypasses Account Status",
  "details" : "For Concrete CMS 9.5.0 and below, OAuth 2.0 Authorization-Code Handler Bypasses Account Status. A user with uIsActive=0 (suspended, banned, terminated employee) can still authenticate via OAuth and receive valid API tokens. ",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "concrete5/concrete5"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "9.5.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-7887"
  }, {
    "type" : "WEB",
    "url" : "https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/concretecms/concretecms"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1287" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-24T21:11:57Z",
    "nvd_published_at" : "2026-05-21T22:16:49Z"
  }
}