CVE-2026-76087 is a high-severity (CVSS 8.2) CWE-639 vulnerability in verbb/formie. A fix is available for verbb/formie — see the affected versions and patch details below.
Formie: Unauthenticated users can overwrite incomplete submissions via submit action
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-76087.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-76087 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
verbb/formie🐘verbb/formieReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
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, 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 ([email protected])
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | verbb/formie | ≥ 3.0.0&&< 3.1.31 | 3.1.31composer require verbb/formie:^3.1.31 |
| 🐘Packagist | verbb/formie | all versions | 2.2.23composer require verbb/formie:^2.2.23 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for verbb/formie, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update verbb/formie to 3.1.31 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-76087 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2026-76087 in your dependencies?
Find it across Packagist, including transitive dependencies.