CVE-2026-76087: Formie Unauthenticated Users Can Overwrite Incomplete Vulnerability

HIGH
Advisory Identifier: GHSA-584p-f93j-wpgc
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CVSS 8.2
CWE-639 CWE-862
Published
Advisory Summary

CVE-2026-76087 is a HIGH (CVSS 8.2) unauthenticated users can overwrite incomplete vulnerability (CWE-639: Authorization Bypass Through User-Controlled Key) affecting Formie libraries in the Packagist ecosystem. The issue involves unauthenticated users can overwrite incomplete submissions via submit action. Remediation is available by upgrading affected packages to version 3.1.31, 2.2.23.

CVE-2026-76087 at a Glance

CVE Identifier CVE-2026-76087
GHSA Identifier GHSA-584p-f93j-wpgc
Severity HIGH
CVSS v3.1 Base Score 8.2
CWE Classification CWE-639: Authorization Bypass Through User-Controlled Key
Affected Product Formie
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 8.2

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

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

How to Fix CVE-2026-76087

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

verbb/formie fixed: 3.1.31 
Upgrade verbb/formie to 3.1.31
verbb/formie fixed: 2.2.23 
Upgrade verbb/formie to 2.2.23
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 verbb/formie

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-76087, inspect your project dependencies for Formie:

inspect dependencies for verbb/formie

Analyze the terminal output to locate any version of Formie in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.1.31), 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 Formie, 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

### Impact The anonymous front-end action `formie/submissions/submit` (`SubmissionsController::actionSubmit`) trusted a client-supplied `submissionId` when loading an incomplete submission, with no session binding, ownership check, or edit token validation. An unauthenticated attacker could enumerate sequential submission IDs and overwrite or hijack another user's in-progress (multi-page / save-for-later) submission. Tampered data could be persisted and forwarded via notifications and integrations when the submission was completed. Completed submissions were not affected (`isIncomplete=true` filter). This is an incomplete remediation of [GHSA-pgxq-p76c-x9cg](https://github.com/advisories?query=GHSA-pgxq-p76c-x9cg), which added edit-token validation to `save-submission` but not to `submit`. ### Patches Fixed in **3.1.31** (Craft 5) and **2.2.23** (Craft 4). When resuming an existing submission on a site request, the submission ID must match the session-bound submission (`Form::getCurrentSubmission()`) or a valid `submissionEditToken` when `editingSubmission` is set. Cross-form submission ID reuse is also rejected. ### Workarounds No reliable workaround without upgrading. Disabling multi-page forms or save-for-later reduces exposure but does not remove the vulnerability. - Reported by Jorge González (jorge@jmilla.es)

CVE-2026-76087 Affected Formie Versions

2 component(s)
Fixed Versions:
3.1.312.2.23
Product / Package Ecosystem Affected Versions Fixed Version
verbb/formie
 Packagist
≥ 3.0.0
< 3.1.31
3.1.31
verbb/formie
 Packagist
< 2.2.23
2.2.23

References

GitHub Advisory / Wiki ADVISORY
https://github.com/verbb/formie/security/advisories/GHSA-584p-f93j-wpgc
Security Fix Commit FIX COMMIT
https://github.com/verbb/formie/commit/323c2fe647a76fbccadf749728ee4ad9420efee1
Security Fix Commit FIX COMMIT
https://github.com/verbb/formie/commit/78a298ac3baf85ac283988dfce9cd42c9b958f16
Formie Source Repository REPOSITORY
https://github.com/verbb/formie
Formie Release RELEASE
https://github.com/verbb/formie/releases/tag/2.2.23
Formie Release RELEASE
https://github.com/verbb/formie/releases/tag/3.1.31

Frequently Asked Questions

What is CVE-2026-76087?
CVE-2026-76087 is a security vulnerability in Formie involving Unauthenticated users can overwrite incomplete submissions via submit action under CWE-639: Authorization Bypass Through User-Controlled Key.
Which Formie versions are affected?
Affected versions include releases prior to 3.1.31, 2.2.23 across affected packages: verbb/formie.
What version fixes CVE-2026-76087?
Upgrading to 3.1.31, 2.2.23 (or the latest patched release for your respective branch) resolves the vulnerability.
Is verbb/formie affected?
Yes, verbb/formie is affected in releases prior to 3.1.31, 2.2.23. Upgrade your dependency to 3.1.31, 2.2.23 or later.
What is the CVSS score of CVE-2026-76087?
CVE-2026-76087 has a CVSS v3.1 base score of 8.2 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N.
What CWE is associated with CVE-2026-76087?
CVE-2026-76087 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 Packagist dependencies for CVE-2026-76087?
Run the dependency tree command: 'inspect dependencies for verbb/formie'. 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-584p-f93j-wpgc",
  "modified" : "2026-09-23T18:36:44Z",
  "published" : "2026-09-23T18:36:44Z",
  "aliases" : [ "CVE-2026-76087" ],
  "summary" : "Formie: Unauthenticated users can overwrite incomplete submissions via submit action",
  "details" : "### Impact\n\nThe anonymous front-end action `formie/submissions/submit` (`SubmissionsController::actionSubmit`) trusted a client-supplied `submissionId` when loading an incomplete submission, with no session binding, ownership check, or edit token validation.\n\nAn unauthenticated attacker could enumerate sequential submission IDs and overwrite or hijack another user's in-progress (multi-page / save-for-later) submission. Tampered data could be persisted and forwarded via notifications and integrations when the submission was completed.\n\nCompleted submissions were not affected (`isIncomplete=true` filter). This is an incomplete remediation of [GHSA-pgxq-p76c-x9cg](https://github.com/advisories?query=GHSA-pgxq-p76c-x9cg), which added edit-token validation to `save-submission` but not to `submit`.\n\n### Patches\n\nFixed in **3.1.31** (Craft 5) and **2.2.23** (Craft 4).\n\nWhen resuming an existing submission on a site request, the submission ID must match the session-bound submission (`Form::getCurrentSubmission()`) or a valid `submissionEditToken` when `editingSubmission` is set. Cross-form submission ID reuse is also rejected.\n\n### Workarounds\n\nNo reliable workaround without upgrading. Disabling multi-page forms or save-for-later reduces exposure but does not remove the vulnerability.\n\n- Reported by Jorge González (jorge@jmilla.es)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "verbb/formie"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.0.0"
      }, {
        "fixed" : "3.1.31"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "verbb/formie"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.2.23"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/verbb/formie/security/advisories/GHSA-584p-f93j-wpgc"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/verbb/formie/commit/323c2fe647a76fbccadf749728ee4ad9420efee1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/verbb/formie/commit/78a298ac3baf85ac283988dfce9cd42c9b958f16"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/verbb/formie"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/verbb/formie/releases/tag/2.2.23"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/verbb/formie/releases/tag/3.1.31"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639", "CWE-862" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-23T18:36:44Z",
    "nvd_published_at" : null
  }
}