OpenBao: LDAPi ldaputil (wrong escape func)
Date: 2026-06
Affected: go/github.com/openbao/openbao, go/github.com/openbao/openbao
Attack vector: other
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-55770
CWE: CWE-90
CVSS: 6.8 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N)

## 1. Description ### Component `sdk/helper/ldaputil/client.go` — the shared LDAP utility library used by both the LDAP authentication backend and OpenLDAP secrets engine to construct LDAP search filters and bind DNs. ### Root Cause The LDAP utility contains a **function selection error** that causes incorrect escaping of user-controlled input in LDAP filter construction. Two lines construct the `bindDN` using `EscapeLDAPValue()`: ```go // Line 191 — UPN Domain path bindDN = fmt.Sprintf("%s@%s", EscapeLDAPValue(username), cfg.UPNDomain) // Line 193 — User DN path bindDN = fmt.Sprintf("%s=%s,%s", cfg.UserAttr, EscapeLDAPValue(username), cfg.UserDN) ``` The problem: `EscapeLDAPValue()` implements **RFC 4514** escaping, which is designed for Distinguished Name (DN) components. It only escapes characters meaningful in DNs: `+`, `,`, `;`, `"`, `\`, `<`, `>`, and leading/trailing spaces. LDAP **search filters** (RFC 4515) have a different set of special characters: `*`, `(`, `)`, `\`, and NUL (`\x00`). None of these are escaped by `EscapeLDAPValue()`. The correct function is `ldap.EscapeFilter()` from the `github.com/go-ldap/ldap/v3` package. The irony: the same file uses `ldap.EscapeFilter()` correctly at lines 225-226 in `RenderUserSearchFilter()` for the `UserFilter` template path, but the `GetUserDN()` function at lines 191-193 uses the wrong escape function. ### Exploitation Mechanics ``` Username: alice)(objectClass=* ↓ EscapeLDAPValue (no-op — no DN special chars)


Mitigations:

Architectural layers (MAESTRO):