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CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

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A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

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Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

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352,427

Total vulnerabilities in the database

CVE-2026-55770 — github.com/openbao/openbao

Improper Neutralization of Special Elements used in an LDAP Query ('LDAP Injection')

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():

// Line 191 — UPN Domain path
bindDN = fmt.Sprintf(&quot;%s@%s&quot;, EscapeLDAPValue(username), cfg.UPNDomain)

// Line 193 — User DN path
bindDN = fmt.Sprintf(&quot;%s=%s,%s&quot;, 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)
alice)(objectClass=*
↓ fmt.Sprintf(&quot;(&amp;(objectClass=user)(sAMAccountName=%s))&quot;, escapedUsername)
(&amp;(objectClass=user)(sAMAccountName=alice)(objectClass=*))
                              ^^ injection point

The filter (&(objectClass=user)(sAMAccountName=alice)(objectClass=*)) is logically equivalent to:

sAMAccountName=alice AND objectClass=user AND objectClass=*

Since all entries match objectClass=*, the filter matches any user entry where sAMAccountName is alice, effectively ignoring the objectClass=user constraint. By crafting more sophisticated injections (e.g., alice)(|(sAMAccountName=admin), the attacker can match arbitrary different user entries.

Preconditions

LDAP authentication backend must be configured
Directory must be Active Directory (UPNDomain path) or use UserDN/UserAttr binding
Attacker controls the username field at login time

2. Proof of Concept

# Login with LDAP injection payload as username
curl -k -X POST \
  -H &quot;Content-Type: application/json&quot; \
  -d &#039;{
    &quot;username&quot;: &quot;alice)(sAMAccountName=*&quot;,
    &quot;password&quot;: &quot;anything&quot;
  }&#039; \
  https://localhost:8200/v1/auth/ldap/login/admin

# LDAP filter constructed:
# (&amp;(objectClass=user)(sAMAccountName=alice)(sAMAccountName=*))
#                   injection ──────────^
# The filter matches the first user with objectClass=user
# If the LDAP server returns admin&#039;s entry first, the token
# is bound to the admin entity, inheriting all admin policies

The LDAP search returns whichever entry the server ranks highest among results. In Active Directory with default sorting, this is often the oldest or alphabetically first user — potentially an administrative account.

3. Impact

| Impact | Detail | |--------|--------| | Confidentiality | Token bound to a different LDAP user (e.g., admin) grants access to all secrets and policies belonging to that entity | | Integrity | Ability to modify secrets, write policies, or configure backends as the impersonated user | | Availability | Low direct impact, but administrative access enables disabling or misconfiguring the entire OpenBao instance |

Likelihood: HIGH — the escape function mismatch is a well-documented antipattern in OWASP LDAP Injection guidance. The attack is trivially exploitable with no special tooling beyond curl.

Why This Is High Severity

The LDAP auth backend is frequently used as a primary authentication method for enterprise OpenBao deployments. A successful LDAP injection against this backend can bypass the entire authentication chain, granting administrative access to the secrets store without needing to compromise an actual admin account.

4. Remediation

Primary Fix: Use ldap.EscapeFilter

Replace EscapeLDAPValue with ldap.EscapeFilter in both filter construction paths:

import &quot;github.com/go-ldap/ldap/v3&quot;

// Line 191 — UPN Domain path
bindDN = fmt.Sprintf(&quot;%s@%s&quot;, ldap.EscapeFilter(username), cfg.UPNDomain)

// Line 193 — User DN path
bindDN = fmt.Sprintf(&quot;%s=%s,%s&quot;, cfg.UserAttr, ldap.EscapeFilter(username), cfg.UserDN)

EscapeLDAPValue is still the correct choice for actual DN construction (where values are used as RDN components rather than filter values), but any value interpolated into an LDAP filter string must use ldap.EscapeFilter.

Audit: All Call Sites

Review all usages of EscapeLDAPValue across the codebase to ensure none are used in filter context:

grep -rn &quot;EscapeLDAPValue&quot; /root/cve-audit/openbao/

Defense-in-Depth

Apply the principle of least privilege to LDAP service accounts used by OpenBao
Use UserFilter with explicit attribute constraints to limit the search scope

Published: Jun 19, 2026
Updated: Jun 20, 2026
CVE: CVE-2026-55770
GHSA: GHSA-6mwx-4547-5vc9
Severity: Medium
Exploit:
CISA KEV:

CVSS v3:

Severity: Medium
Score: 6.8
AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

CWEs:

CWE-90

OWASP TOP 10:

A1 - Injection

Affected Software
References

Software	From	Fixed in
github.com/openbao/openbao	0.1.0	2.5.4.x
github.com/openbao/openbao	-	0.0.0-20260617104213-10b7825c714c

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.