PAC4J: Improper Neutralization of Special Elements used in an LDAP Query
CVE-2026-40459 is a high-severity improper neutralization of special elements used in an LDAP query vulnerability in PAC4J, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 4.5.10, 5.7.10, 6.4.1 as the first without the flaw, so updating PAC4J to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.62% chance of exploitation within 30 days, higher than 50% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update PAC4J to 4.5.10 or 5.7.10 or 6.4.1, whichever matches your release line, or a later version.
- Read the advisory on pac4j.org for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| PAC4J | PAC4J | 4.0 up to, but not including, 4.5.10; 5.0 up to, but not including, 5.7.10; 6.0 up to, but not including, 6.4.1 | 4.5.10, 5.7.10, 6.4.1 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.7 | High | CNA (cert.pl) |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
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, 5.7.10 and 6.4.1
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in an LDAP Query
The product constructs all or part of an LDAP query using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended LDAP query when it is sent to a downstream component.
More Improper Neutralization of Special Elements used in an LDAP Query vulnerabilities (CWE-90)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cert.pl/en/posts/2026/04/CVE-2026-40458/Third Party Advisory
Other vulnerabilities in PAC4J
- 8.1 High severity
- 8.1 High severity
- 9.2 Critical severity
Recent Improper Neutralization of Special Elements used in an LDAP Query vulnerabilities
- 8.2 High severity
- 9.6 Critical severity
- 8.2 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
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