CVE-2021-46876 is a medium-severity (CVSS 5.3) CWE-203 vulnerability in ezsystems/ezpublish-kernel. A fix is available for ezsystems/ezpublish-kernel — see the affected versions and patch details below.
/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.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-46876 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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 | 6.13.8.1composer require ezsystems/ezpublish-kernel:^6.13.8.1 |
| 🐘Packagist | ezsystems/ezpublish-kernel | ≥ 7.5.0&&< 7.5.15.1 | 7.5.15.1composer require ezsystems/ezpublish-kernel:^7.5.15.1 |
Affected Products
ez platform kernelibexaDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ezsystems/ezpublish-kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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.
Frequently Asked Questions
Is CVE-2021-46876 in your dependencies?
Find it across Packagist, including transitive dependencies.