---
id: "CVE-2026-48057"
page: "https://infrastack.ai/live/CVE-2026-48057"
kind: "vulnerability"
aliases: ["CVE-2026-48057"]
title: "Botan: multi-value RDN flattening lets name constraints be bypassed"
severity: "low"
cvss: 2.1
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["botan", "c++", "internal-pki", "package", "x.509"]
not_affected_if: ["no-dn-name-constraints", "public-web-pki", "subjectaltname-present"]
published_at: "2026-11-06T22:17:53+00:00"
first_seen_at: "2026-11-06T22:44:32+00:00"
updated_at: "2026-11-06T22:44:59+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-48057", "first_seen_at": "2026-11-06T22:44:32+00:00"}]
exploit_sources: []
---

# Botan: multi-value RDN flattening lets name constraints be bypassed

Link for people: https://infrastack.ai/live/CVE-2026-48057 (this .md is for agents)

Botan is a C++ cryptography library whose X.509 distinguished name decoder loses multi-value RDN grouping before name-constraint checks. An attacker holding a name-constrained intermediate CA can issue a certificate whose second Common Name is accepted as a hostname, provided the certificate has no subjectAlternativeName.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Botan version in use with `botan version` or the library's version header
- Look for DN name constraints in certificate validation paths of internal PKI deployments
- Check whether the application relies on Common Name hostname matching for certificates without subjectAlternativeName

## Fix

- Botan: `3.13.0`

## Timeline

- 2026-11-06T22:44:32+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-48057

## Documents

- [advisory] Vendor advisory: github.com https://github.com/randombit/botan/security/advisories/GHSA-3mh2-26h4-wrqc
- [fix] Patch: github.com https://github.com/randombit/botan/commit/a22260c368373a134ff9778b9d8781edb2e1eb99

## From the sources

Botan is a C++ cryptography library. Prior to 3.13.0, Botan's X.509 Distinguished Name decoder flattens the Attribute-Value Assertions in each Relative Distinguished Name and loses multi-value RDN grouping before DN name-constraint enforcement. An attacker controlling a name-constrained intermediate CA can issue a certificate with a multi-value RDN whose first Common Name matches the permitted constraint and whose second Common Name is attacker-chosen, causing the constraint check to accept the flattened first value. If the certificate contains no subjectAlternativeName extension, the second Common Name can then be accepted as a hostname; Botan does not fall back to Common Name hostname matching when any subjectAlternativeName is present. The exposure is limited to deployments using DN name constraints, which are uncommon outside internal PKIs, and to certificates without a subjectAlternativeName. This issue is fixed in version 3.13.0.

---

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