# CVE-2026-35563: Apache Directory LDAP API lacks server certificate verification for LDAP hostnames

> Attackers can impersonate LDAP servers via MITM due to missing hostname verification, allowing data interception or modification.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:H/SI:L/SA:L`)
- **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:** 1 Jun 2026
- **Updated:** 1 Jun 2026
- **Also known as:** CLEANSTART-2026-EU32419, DEBIAN-CVE-2026-35563, GHSA-85rw-g4f4-jprr, UBUNTU-CVE-2026-35563

## What is CVE-2026-35563?

CVE-2026-35563 is a high-severity vulnerability in Apache Directory LDAP API, published on 1 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

It was identified that the LDAP client implementation in version 2.1.7 does not verify if the server certificate matches the intended LDAP 
hostname. While the underlying code validates the certificate chain 
against a trusted authority, the absence of endpoint identification 
allows a valid certificate issued for an entirely unrelated host to be 
improperly accepted. This oversight leaves the connection highly 
vulnerable to server impersonation and complete connection compromise.

The
 root cause of this vulnerability lies in the incomplete TLS server 
identity verification within the LDAP client implementation.

The attacker requires MITM capability on the network to exploit this vulnerability. This attacker must be able to present a certificate trusted by the client's configured trust store.

The hostname verification has been enforced in the new version of the LDAP API

Weakness: CWE-297 (Improper Validation of Certificate with Host Mismatch)

## Which versions are affected by CVE-2026-35563?

2 open source packages ship an affected version, including org.apache.directory.api:api-ldap-client-api. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.apache.directory.api:api-ldap-client-api` | Maven | From 2.0.0 | 2.1.8 |
| `org.apache.directory.api:api-ldap-client-api` | Maven | From 2.0.0 | 2.1.8 |

Products: Apache Directory Ldap Api.

## How do I fix CVE-2026-35563?

Upgrade org.apache.directory.api:api-ldap-client-api to 2.1.8 or later.

## Is CVE-2026-35563 being exploited?

There is no known exploitation of CVE-2026-35563 in the wild and no public exploit code.

## Other vulnerabilities in Apache Directory LDAP API

- [CVE-2018-1337](https://insights.sbomify.com/CVE-2018-1337/): Credential leak in org.apache.directory.api:apache-ldap-api (critical 9.8)
- [CVE-2015-3250](https://insights.sbomify.com/CVE-2015-3250/): Exposure of Sensitive Information to an Unauthorized Actor in Apache Directory LDAP API (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-35563 and fix it if it is affected.

What it is: CVE-2026-35563 is a high-severity vulnerability in Apache Directory LDAP API, published on 1 Jun 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-2026-35563 in the wild and no public exploit code.

Affected packages and fixed versions:
- org.apache.directory.api:api-ldap-client-api (Maven): affected from 2.0.0; fixed in 2.1.8
- org.apache.directory.api:api-ldap-client-api (Maven): affected from 2.0.0; fixed in 2.1.8

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-2026-35563/ (Markdown: https://insights.sbomify.com/CVE-2026-35563/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-35563
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-35563
- OSV: https://osv.dev/vulnerability/CVE-2026-35563

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-35563/
Summaries are generated and may contain mistakes; the official description above is the record.