CVE-2026-55962Network attack vector

Client authentication bypass via misplaced certificate exemption

Published Jun 25, 2026 · Updated Jun 25, 2026

Improper authentication in wolfSSL 5.5.4 through 5.9.1 allows remote authenticated users to bypass TLS 1.3 post-handshake client authentication. While a post-handshake CertificateRequest remains outstanding, the server incorrectly reuses an initial-handshake exemption and accepts Finished without Certificate or CertificateVerify. Exposure requires a TLS 1.3 server built with post-handshake authentication, WOLFSSL_VERIFY_POST_HANDSHAKE enabled, and a call to wolfSSL_request_certificate(); clients and other servers are unaffected.

CVSS severity6.0
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in wolfSSL 5.5.4 through 5.9.1 allows remote authenticated users to bypass TLS 1.3 post-handshake client authentication. While a post-handshake CertificateRequest remains outstanding, the server incorrectly reuses an initial-handshake exemption and accepts Finished without Certificate or CertificateVerify. Exposure requires a TLS 1.3 server built with post-handshake authentication, WOLFSSL_VERIFY_POST_HANDSHAKE enabled, and a call to wolfSSL_request_certificate(); clients and other servers are unaffected.

The record

CVE
CVE-2026-55962
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-287, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 25, 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=5.5.4 <=5.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

wolfSSL · wolfSSLversion=5.5.4 <=5.9.1

Published CVSS scores

6.0wolfSSL Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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