# CVE-2026-53658: Fabric CA: LDAP Injection via Unescaped Username in GetUser Filter

> An unauthenticated attacker can inject LDAP metacharacters into the username field to bypass authentication checks in Hyperledger Fabric CA when using an LDAP backend.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-xghw-p77p-3r7x, GO-2026-6234

## What is CVE-2026-53658?

CVE-2026-53658 is a medium-severity vulnerability in hyperledger fabric-ca, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Fabric CA is a Certificate Authority for Hyperledger Fabric. Prior to 1.5.21, when fabric-ca is configured with an LDAP backend, Client.GetUser in lib/server/ldap/client.go inserts the username from HTTP Basic authentication into the LDAP uid search UserFilter without escaping LDAP metacharacters. An unauthenticated attacker with network access to the CA enrollment endpoint can alter the LDAP search before password validation and potentially steer authentication attempts toward a victim account. Deployments that do not use an LDAP backend are unaffected. This issue is fixed in version 1.5.21.

Weakness: CWE-90 (Improper Neutralization of Special Elements used in an LDAP Query)

## Which versions are affected by CVE-2026-53658?

3 open source packages ship an affected version, including github.com/hyperledger/fabric-ca.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/hyperledger/fabric-ca` | Go | All versions | 1.5.21 |
| `github.com/hyperledger/fabric-ca` | Go | All versions | 1.5.21 |
| `github.com/hyperledger/fabric-ca` | Go | All versions | 1.5.21 |

## How do I fix CVE-2026-53658?

Upgrade github.com/hyperledger/fabric-ca to 1.5.21 or later.

## Is CVE-2026-53658 being exploited?

There is no known exploitation of CVE-2026-53658 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53658 and fix it if it is affected.

What it is: CVE-2026-53658 is a medium-severity vulnerability in hyperledger fabric-ca, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-53658 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/hyperledger/fabric-ca (Go): affected all versions; fixed in 1.5.21
- github.com/hyperledger/fabric-ca (Go): affected all versions; fixed in 1.5.21
- github.com/hyperledger/fabric-ca (Go): affected all versions; fixed in 1.5.21

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-2026-53658/ (Markdown: https://insights.sbomify.com/CVE-2026-53658/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53658
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53658
- OSV: https://osv.dev/vulnerability/CVE-2026-53658

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53658/
Summaries are generated and may contain mistakes; the official description above is the record.