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BotanApplication · Botan Project

CVE-2026-34582

CRITICAL · 9.1 CVSS v3.1 Published 2026-04-07
Fix available
A fix is available. Upgrade to after 3.11.0 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 is a C++ cryptography library. Prior to version 3.11.1, the TLS 1.3 implementation allowed ApplicationData records to be processed prior to the Finished message being received. A server which is attempting to enforce client authentication via certificates can by bypassed by a client which entirely omits Certificate, CertificateVerify, and the Finished message and instead sends application data records. This vulnerability is fixed in 3.11.1.

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

In Botan versions prior to 3.11.1, the TLS 1.3 implementation incorrectly allowed ApplicationData records to be processed before the Finished message was received. This violates TLS 1.3 protocol ordering and allows a client to bypass client certificate authentication by omitting the Certificate, CertificateVerify, and Finished messages entirely while sending application data directly.

MitigationUpgrade Botan to version 3.11.1 or later to ensure proper TLS 1.3 handshake sequencing and client certificate authentication enforcement.

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:>= 3.0.0, <= 3.11.0

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
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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 if Botan TLS library is in use
    Search for files named 'botan' or 'libbotan' in your system, or check package manager for installed botan packages. Also check application dependencies for botan references.
    Affected if Botan library is present in the environment
  2. Determine installed Botan version
    Run 'botan --version' or check the library file version (e.g., libbotan-3.so.3.11.0). For npm packages, run 'npm list botan'. For other language bindings, consult the appropriate package query command.
    Affected if Version is >= 3.0.0 and <= 3.11.0
  3. Verify TLS 1.3 is enabled
    Check application configuration files or code for TLS 1.3 protocol configuration. Look for settings like 'tls_version' or 'max_tls_version' set to 1.3, or examine TLS handshake logs for 'TLSv1.3' in cipher negotiation.
    Affected if TLS 1.3 is enabled and in use
  4. Confirm client certificate authentication is required
    Check TLS server configuration for 'verify_client' or 'request_client_cert' set to 'required' or 'mandatory'. Examine application code for TLS_CERT_REQUIRED or similar settings.
    Affected if Server requires or requests client certificate authentication

Environment is affected if Botan TLS library versions 3.0.0 through 3.11.0 are in use with TLS 1.3 and client certificate authentication is enabled.

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 3.11.0
Interim mitigation

Upgrade Botan to version 3.11.1 or later to ensure proper TLS 1.3 handshake sequencing and client certificate authentication enforcement.

Recommended fix High confidence

Botan 3.11.1

  1. 1. Identify the current version of Botan library in use by checking project dependencies or build configuration
  2. 2. Update the Botan library to version 3.11.1 or later using the appropriate package manager or build system (e.g., package manager like apt/yum, or rebuild from source)
  3. 3. Rebuild and redeploy any applications that link against the Botan library
  4. 4. Verify the TLS 1.3 implementation correctly enforces the proper handshake order, ensuring ApplicationData cannot be processed before the Finished message is received
  5. 5. If using client certificate authentication in TLS 1.3, test that the authentication is properly enforced and cannot be bypassed
Caveat Minor version upgrade within 3.x series; review release notes for any API/behavior changes

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

Fix this in Botan Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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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-2026-34582 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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