GHSA-8cr7-r8qw-gp3c — baserproject/basercms
MEDIUMGHSA-8cr7-r8qw-gp3c is a medium-severity (CVSS 5.3) CWE-285 vulnerability in baserproject/basercms. A fix is available for baserproject/basercms — see the affected versions and patch details below.
baserCMS has Mail Form Acceptance Bypass via Public API
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-8cr7-r8qw-gp3c.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-8cr7-r8qw-gp3c plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,238 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
baserproject/basercmsReal-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
Summary
A public mail submission API allows unauthenticated users to submit mail form entries even when the corresponding form is not accepting submissions. This bypasses administrative controls intended to stop form intake and enables spam or abuse via the API.
Details
In baserCMS, mail form submissions through the front-end UI are guarded by acceptance checks implemented in MailFrontService::isAccepting(), which ensures that the mail form is currently accepting submissions (e.g. within its configured publish/acceptance window).
These checks are enforced in the UI flow handled by MailController::index() and MailController::confirm()
(e.g. plugins/bc-mail/src/Controller/MailController.php).
However, the public API endpoint:
plugins/bc-mail/src/Controller/Api/MailMessagesController.php::add()
does not invoke MailFrontService::isAccepting() and does not verify whether the mail form is currently accepting submissions. As a result, the API accepts submissions regardless of the form’s acceptance state.
The endpoint does not require authentication. A valid CSRF cookie and token pair is sufficient to create a mail message. This allows submissions even when administrators intentionally disable or close the mail form via the admin UI.
PoC
- In the admin UI, configure a mail form so that it is not accepting submissions (e.g. outside its acceptance period or explicitly closed).
- Obtain a CSRF cookie by accessing the site root:
curl -sS -D - -o - -c /tmp/basercms_cookies.txt 'http://localhost/'
- Extract the CSRF token from the
csrfTokencookie and submit a POST request to the public API endpoint:
curl -sS -D - -o - -X POST 'http://localhost/baser/api/bc-mail/mail_messages/add/1.json'
-H 'Content-Type: application/x-www-form-urlencoded'
-H 'Referer: http://localhost/'
-H 'X-CSRF-Token: <csrf-token-from-cookie>'
-b /tmp/basercms_cookies.txt
--data-urlencode 'name_1=Test'
--data-urlencode 'name_2=User'
--data-urlencode '[email protected]'
--data-urlencode '[email protected]'
--data-urlencode 'category[]=資料請求'
--data-urlencode 'root=検索エンジン'
--data-urlencode 'message=API bypass test'
- The server responds with
200 OKand creates a mail message, even though the form is configured to reject submissions.
Impact
This is an access control / business logic bypass vulnerability.
Administrators rely on the mail form acceptance settings to temporarily or permanently stop form intake (e.g. during maintenance, incidents, or spam attacks). This vulnerability allows attackers to bypass those controls via the public API, enabling unauthorized mail submissions, spam, and operational disruption.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | baserproject/basercms | all versions | 5.2.3composer require baserproject/basercms:^5.2.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for baserproject/basercms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update baserproject/basercms to 5.2.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8cr7-r8qw-gp3c is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-8cr7-r8qw-gp3c can be triaged on real exposure rather than presence alone.
Tailored to GHSA-8cr7-r8qw-gp3c. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-8cr7-r8qw-gp3c in your dependencies?
O3 Security finds GHSA-8cr7-r8qw-gp3c across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.