CVE-2021-46876 is a medium-severity (CVSS 5.3) CWE-203 vulnerability in ezsystems/ezpublish-kernel. O3 Security confirms whether CVE-2021-46876 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
/user/sessions endpoint allows detecting valid accounts
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-2021-46876.
Real-World Exposure
ezsystems/ezpublish-kernel🐘ezsystems/ezpublish-kernelReal-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
This Security Advisory is about a vulnerability in eZ Platform v1.13, v2.5, and v3.2, and in Ibexa DXP and Ibexa Open Source v3.3. The /user/sessions endpoint can let an attacker detect if a given username or email refers to a valid account. This can be detected through differences in the response data or response time of certain requests. The fix ensures neither attack is possible. The fix is distributed via Composer.
If you come across a security issue in our products, here is how you can report it to us: https://doc.ibexa.co/en/latest/guide/reporting_issues/#toc
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | ezsystems/ezpublish-kernel | ≥ 6.13.0&&< 6.13.8.1 | 6.13.8.1 |
| 🐘Packagist | ezsystems/ezpublish-kernel | ≥ 7.5.0&&< 7.5.15.1 | 7.5.15.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ezsystems/ezpublish-kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update ezsystems/ezpublish-kernel to 6.13.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-46876 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 pinpoints whether CVE-2021-46876 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-46876. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-46876 in your dependencies?
O3 detects CVE-2021-46876 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.