# CVE-2026-40459: LDAP Injection in PAC4J

> A low-privileged attacker can inject LDAP syntax into PAC4J search parameters to perform unauthorized directory queries and operations.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Apr 2026
- **Updated:** 17 Apr 2026
- **Also known as:** CLEANSTART-2026-YN41310, GHSA-3jrj-7493-fgq2

## What is CVE-2026-40459?

CVE-2026-40459 is a high-severity vulnerability in PAC4J, published on 17 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### 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

Weakness: CWE-90 (Improper Neutralization of Special Elements used in an LDAP Query)

## Which versions are affected by CVE-2026-40459?

It affects 1 product.


Products: Pac4j Pac4j.

## How do I fix CVE-2026-40459?

Upgrade to a fixed version.

## Is CVE-2026-40459 being exploited?

There is no known exploitation of CVE-2026-40459 in the wild and no public exploit code.

## Other vulnerabilities in PAC4J

- [CVE-2021-44878](https://insights.sbomify.com/CVE-2021-44878/): Pac4j token validation bypass if OpenID Connect provider supports none algorithm (high 7.5)
- [CVE-2026-40458](https://insights.sbomify.com/CVE-2026-40458/): Cross-Site Request Forgery in PAC4J (high 7.0)
- [CVE-2019-10755](https://insights.sbomify.com/CVE-2019-10755/): Use of Cryptographically Weak Pseudo-Random Number Generator in org.pac4j:pac4j-saml (medium 4.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40459 and fix it if it is affected.

What it is: CVE-2026-40459 is a high-severity vulnerability in PAC4J, published on 17 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-40459 in the wild and no public exploit code.

Affected product: PAC4J. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-40459/ (Markdown: https://insights.sbomify.com/CVE-2026-40459/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40459
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40459
- OSV: https://osv.dev/vulnerability/CVE-2026-40459

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40459/
Summaries are generated and may contain mistakes; the official description above is the record.