light-4j: Authentication bypass via empty LDAP password in Basic Auth
Summary
The Basic Auth handler of networknt light-4j from 2.1.5 before 2.4.0 accepts a Basic Authorization header with a known username and an empty password. This triggers an unauthenticated LDAP bind that is accepted as successful authentication, so an unauthenticated attacker can log in as LDAP or Active Directory delegated users. The flaw applies only to custom Java services that use light-4j Basic Auth with LDAP/AD delegation and whose directory accepts unauthenticated binds.
Affected
- networknt light-4j from 2.1.5 before 2.4.0
- Maven modules such as com.networknt:basic-auth and the ldap-util component (according to the OSV feed)
- Default configuration: not affected, per the CVE record
Fixed in
- light-4j 2.4.0 (release 2.4.0, fix tracked in issue #2804 and PR #2805)
- Patch for the 2.3.x line: Unknown.
Workaround
- No vendor-published workaround.
- For unpatched builds, LDAP administrators may disallow unauthenticated bind requests. This is a general LDAP measure from another project's advisory and has not been tested for light-4j.
Exploitation
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
- Not marked as known exploited in the sources reviewed.
- No public proof of concept found in the searches performed; this does not prove that none exists.
Our recommendation
- Inventory Java services that use light-4j, including Maven dependencies basic-auth and ldap-util, and any light-lambda-native deployments.
- Upgrade to light-4j 2.4.0, rebuild, and check forks or copied code.
- Confirm that the LDAP/AD configuration does not accept unauthenticated binds.
- Review authentication logs for successful logins of LDAP-delegated accounts without matching password events.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- BasicAuthHandler.java (light-4j 2.3.7) github.com
- LdapUtil.java (light-4j 2.3.7) github.com
- light-4j release 2.4.0 github.com
- light-4j issue #2804 github.com
- light-4j pull request #2805 github.com
- light-4j issue #2807 (follow-up hardening) github.com
- VulnCheck advisory www.vulncheck.com
- OSV record CVE-2026-113682 (Vulners) vulners.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 06:16.
Original description (NVD)
Networknt light-4j from 2.1.5 before 2.4.0 contains an authentication bypass vulnerability in BasicAuthHandler that allows unauthenticated attackers to log in as LDAP/AD-delegated users. Attackers can send a Basic Authorization header with a known username and empty password, triggering an unauthenticated LDAP bind that is accepted as successful authentication.
NVD references (7)
- https://github.com/networknt/light-4j/blob/2.3.7/basic-auth/src/main/java/com/networknt/basicauth/BasicAuthHa…
- https://github.com/networknt/light-4j/blob/2.3.7/ldap-util/src/main/java/com/networknt/ldap/LdapUtil.java#L15…
- https://github.com/networknt/light-4j/commit/54743badb34260b76ed131d8b6a4f60210cc3673
- https://github.com/networknt/light-4j/issues/2804
- https://github.com/networknt/light-4j/pull/2805
- https://github.com/networknt/light-4j/releases/tag/2.4.0
- https://www.vulncheck.com/advisories/networknt-light-4j-2.1.5-before-2.4.0-authentication-bypass-via-empty-ld…
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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