dbcve.org
BotanApplication · Botan Project

CVE-2018-9127

CRITICAL · 9.8 CVSS v3.0 Published 2018-04-02
Fix available
A fix is available. Upgrade to after 2.4.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Botan 2.2.0 - 2.4.0 (fixed in 2.5.0) improperly handled wildcard certificates and could accept certain certificates as valid for hostnames when, under RFC 6125 rules, they should not match. This only affects certificates issued to the same domain as the host, so to impersonate a host one must already have a wildcard certificate matching other hosts in the same domain. For example, b*.example.com would match some hostnames that do not begin with a 'b' character.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Botan library versions 2.2.0-2.4.0 incorrectly implemented RFC 6125 wildcard certificate matching, allowing certificates with wildcards like b*.example.com to match hostnames that do not begin with 'b'. This certificate validation bypass could enable impersonation attacks against domains where an attacker already possesses a wildcard certificate for that domain.

MitigationUpgrade Botan library to version 2.5.0 or later which contains the corrected wildcard certificate matching implementation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
BotanApplication
Affected:>= 2.2.0, <= 2.4.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Botan library presence
    Search for the Botan library binary files (libbotan on Linux, botan.dll on Windows, or libbotan.so on Unix systems) in the system or within application dependencies. Also check if any applications link against libbotan using 'ldd' on Linux or dependency walkers on Windows.
    Affected if Botan library is present in the environment
  2. Determine installed Botan version
    Run 'botan --version' from command line if the Botan CLI tool is installed, or examine the library file metadata/version info. Check any package manager records if installed via apt, yum, or similar.
    Affected if The version number is 2.2.0, 2.3.0, 2.4.0, or any version between these values
  3. Verify certificate validation is in use
    Inspect application configuration files or source code to confirm that Botan is being used for TLS connections or X.509 certificate hostname validation. Look for Botan::TLS::Session or Botan::X509::Certificate usage in the application.
    Affected if Applications or services use Botan for TLS or certificate hostname validation
  4. Check for wildcard certificate usage
    Review the certificates being presented or configured in the environment to determine if any contain wildcards in the subject alternative name (SAN) field, such as '*.example.com' or 'b*.example.com'.
    Affected if Wildcard certificates are being validated against hostnames using the affected Botan version

If the installed Botan library version is between 2.2.0 and 2.4.0 and the application uses it to validate wildcard certificates against hostnames, the environment is vulnerable to CVE-2018-9127.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 2.4.0
Interim mitigation

Upgrade Botan library to version 2.5.0 or later which contains the corrected wildcard certificate matching implementation.

Recommended fix High confidence

2.5.0 or later

  1. 1. Identify the current version of Botan library in use by checking project dependencies or running 'boton version' if CLI is available
  2. 2. Obtain Botan version 2.5.0 or later from the official source at botan.randombit.net or trusted package repositories
  3. 3. Replace the existing Botan library binaries or source files with the new version
  4. 4. Rebuild and recompile any applications that link against the Botan library
  5. 5. Re-run any TLS/SSL functionality tests to verify certificate validation now correctly enforces RFC 6125 wildcard matching rules
  6. 6. Deploy the updated application

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Botan Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,970
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,752.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2018-9127 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-9127 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data