CVE-2026-35563

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

CVSS v3.1 Score

8.5

HIGH

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.08%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-297 CWE-297

Affected Products

Vendor	Product	Versions
apache	directory_ldap_api	2.0.0 — 2.1.7

References

Advisories & Patches

https://lists.apache.org/thread/5rc2nzqxp1m9wknyf93r8dnp46fhc1nn

Other References

http://www.openwall.com/lists/oss-security/2026/06/01/2

Frequently Asked Questions

What is CVE-2026-35563? +

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 It has a CVSS v3.1 base score of 8.5 (HIGH).

How severe is CVE-2026-35563? +

CVE-2026-35563 has a CVSS v3.1 score of 8.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0018, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-35563? +

CVE-2026-35563 affects products from apache, specifically: directory_ldap_api. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-35563? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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