Cyber Resilience

CVE-2026-40459

Pac4J 4.0.0 – 4.5.10

Published
17 April 2026
Modified
20 April 2026
Patch / advisory
View advisory
CVSS Score v4 8.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0061 48th percentile
Risk Priority 40 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-40459 is a high-severity LDAP Injection (CWE-90) vulnerability in Pac4J Pac4J. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 48th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-40459 is an LDAP injection vulnerability affecting the PAC4J security library, specifically in multiple methods that handle ID-based search parameters. Published on 2026-04-17, it allows injection of crafted LDAP syntax due to insufficient input validation, as classified under CWE-90. The vulnerability carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), indicating high severity with potential for significant confidentiality, integrity, and availability impacts.

A low-privileged remote attacker can exploit this vulnerability over the network with low complexity and no user interaction required. By injecting malicious LDAP syntax into affected search parameters, the attacker can execute unauthorized LDAP queries against the directory service, potentially leading to arbitrary directory operations such as data exfiltration, modification, or deletion.

PAC4J has addressed the issue in versions 4.5.10, 5.7.10, and 6.4.1. Security advisories, including the official PAC4J blog post and a CERT.PL entry, detail the vulnerability and recommend upgrading to these patched releases for mitigation.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

PAC4J is vulnerable to LDAP Injection in multiple methods. A low-privileged remote attacker can inject crafted LDAP syntax into ID-based search parameters, potentially resulting in unauthorized LDAP queries and arbitrary directory operations. This issue was fixed in PAC4J versions 4.5.10,…

more

5.7.10 and 6.4.1

CWE(s)
CWE-90

Related Threats

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-40458Same product: Pac4J Pac4J
CVE-2026-31828Shared CWE-90
CVE-2023-3447Shared CWE-90
CVE-2024-27310Shared CWE-90
CVE-2026-1498Shared CWE-90
CVE-2026-45559Shared CWE-90
CVE-2026-49268Shared CWE-90
CVE-2025-52575Shared CWE-90
CVE-2026-59652Shared CWE-90
CVE-2026-27860Shared CWE-90

Affected Assets

pac4j
pac4j
4.0.0 — 4.5.10 · 5.0.0 — 5.7.10 · 6.0.0 — 6.4.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.2.6

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover LDAP injection flaws through static analysis or crafted test cases.

SI-10 Information Input Validation good match

Input validation directly stops untrusted data from reaching an LDAP query builder without neutralization of special characters.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles require safe query construction and escaping that structurally prevents LDAP injection.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 partial match
prevents

Secure SDLC practices directly require input neutralization and query parameterization to prevent LDAP injection.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and query construction practices that directly prevent LDAP injection.

A.8.26 Application security requirements partial match
prevents

Application security requirements include explicit rules for safe construction of directory queries, mitigating LDAP injection.

A.8.28 Secure coding partial match
prevents

Secure coding standards require proper neutralization of LDAP special characters, directly eliminating this weakness.

A.8.29 Security testing in development and acceptance partial match
finds

Security testing in development catches LDAP injection via dynamic analysis or fuzzing, but does not prevent it at the source.

A.8.27 Secure system architecture and engineering principles none match
mitigates

Secure architecture principles encourage safe query interfaces but do not prescribe the specific coding controls needed for LDAP injection.

References