CVE-2026-34582Network attack vector

Client authentication bypass via premature application data

Published Apr 7, 2026 · Updated Apr 7, 2026

Authentication bypass in Randombit Botan 3.0.0 through 3.11.0 allows remote attackers to submit application data without a client certificate. Channel_Impl_13::from_peer passed ApplicationData record fragments to tls_record_received without first checking that the cipher state permitted application traffic. The server must use TLS 1.3 certificate-based client authentication; omitting Certificate, CertificateVerify, and Finished grants unauthorized application-layer access.

CVSS severity8.7
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Randombit Botan 3.0.0 through 3.11.0 allows remote attackers to submit application data without a client certificate. Channel_Impl_13::from_peer passed ApplicationData record fragments to tls_record_received without first checking that the cipher state permitted application traffic. The server must use TLS 1.3 certificate-based client authentication; omitting Certificate, CertificateVerify, and Finished grants unauthorized application-layer access.

The record

CVE
CVE-2026-34582
Published
Apr 7, 2026
Updated
Apr 7, 2026
Vendor
Botan Project
Product
Botan
Classifications
CWE-841, CWE-166, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.11.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Botan Project · Botanversion=< 3.11.1

Published CVSS scores

8.7GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-841Improper Enforcement of Behavioral Workflow
CWE-166Improper Handling of Missing Special Element
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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