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EUVD-2026-252746

2026-10-06T20:25:49.213031+00:00

EUVD-2026-252746

fkie_cve-2025-59154

2026-10-06T20:25:49.213069+00:00

Openfire is an XMPP server licensed under the Open Source Apache License. Openfire’s SASL EXTERNAL mechanism for client TLS authentication contains a vulnerability in how it extracts user identities from X.509 certificates. Instead of parsing the structured ASN.1 data, the code calls X509Certificate.getSubjectDN().getName() and applies a regex to look for CN=. This method produces a provider-dependent string that does not escape special characters. In SunJSSE (sun.security.x509.X500Name), for example, commas and equals signs inside attribute values are not escaped. As a result, a malicious certificate can embed CN= inside another attribute value (e.g. OU="CN=admin,"). The regex will incorrectly interpret this as a legitimate Common Name and extract admin. If SASL EXTERNAL is enabled and configured to map CNs to user accounts, this allows the attacker to impersonate another user. The fix is included in Openfire 5.0.2 and 5.1.0.

GHSA-w252-645g-87mp — Openfire has potential identity spoofing issue via unsafe CN parsing

2026-10-06T20:25:49.213113+00:00

Affected: Maven: org.igniterealtime.openfire:xmppserver

## Summary

Identity spoofing in X.509 client certificate authentication in Openfire allows internal attackers to impersonate other users via crafted certificate subject attributes, due to regex-based extraction of CN from an unescaped, provider-dependent DN string.

## Analysis

Openfire’s SASL EXTERNAL mechanism for client TLS authentication contains a vulnerability in how it extracts user identities from X.509 certificates. Instead of parsing the structured ASN.1 data, the code calls `X509Certificate.getSubjectDN().getName()` and applies a regex to look for `CN=`. This method produces a provider-dependent string that does not escape special characters. In SunJSSE (`sun.security.x509.X500Name`), for example, commas and equals signs inside attribute values are not escaped.

As a result, a malicious certificate can embed `CN=` inside another attribute value (e.g. `OU="CN=admin,"`). The regex will incorrectly interpret this as a legitimate Common Name and extract admin. If SASL EXTERNAL is enabled and configured to map CNs to user accounts, this allows the attacker to impersonate another user.

## Impact

When there is no explicit configuration override, Openfire defaults to using certificate attributes as follows:

- Server-to-server certificates: first the Subject Alternative Name (SAN), and if that is not available, the Common Name (CN). - Client-to-server certificates: only the Common Name (CN).

Use of CN for identity mapping was phased out by the CA/Browser Forum. CAB F…