CVE-2023-39343 is a medium-severity (CVSS 4.3) CWE-204 vulnerability in sulu/sulu. A fix is available for sulu/sulu — see the affected versions and patch details below.
Sulu Observable Response Discrepancy on Admin Login
Exploitation Status
No confirmed exploitation observed yet
- 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-2023-39343.
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
CVE-2023-39343 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 378,567 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
sulu/suluReal-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
It allows over the Admin Login form to detect which user (username, email) exists and which one do not exist.
Impacted by this issue are Sulu installation >= 2.5.0 and <2.5.10 using the newer Symfony Security System which is default since Symfony 6.0 but can be enabled in Symfony 5.4. Sulu Installation not using the old Symfony 5.4 security System and previous version are not impacted by this Security issue.
Patches
The problem has been patched in version 2.5.10.
Workarounds
Create a custom AuthenticationFailureHandler which does not return the $exception->getMessage(); instead the $exception->getMessageKey();
References
Currently no references.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | sulu/sulu | ≥ 2.5.0&&< 2.5.10 | 2.5.10composer require sulu/sulu:^2.5.10 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sulu/sulu, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update sulu/sulu to 2.5.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-39343 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 CVE-2023-39343 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-39343. 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-2023-39343 in your dependencies?
O3 Security finds CVE-2023-39343 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.