CVE-2026-6091Network attack vector

Trust bypass via unverified partial-chain terminal

Published Jun 25, 2026 · Updated Jun 25, 2026

Improper certificate validation in wolfSSL 5.7.4 through 5.9.1 allows remote authenticated users to bypass certificate-chain trust validation. The partial-chain fallback in wolfSSL_X509_verify_cert accepts the current terminal certificate without checking that it belongs to the original X509_STORE trust set. Reachability requires OPENSSL_EXTRA, X509_V_FLAG_PARTIAL_CHAIN, and a peer-supplied intermediate; acceptance grants the certificate the integrity authority of a trusted anchor.

CVSS severity6.0
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in wolfSSL 5.7.4 through 5.9.1 allows remote authenticated users to bypass certificate-chain trust validation. The partial-chain fallback in wolfSSL_X509_verify_cert accepts the current terminal certificate without checking that it belongs to the original X509_STORE trust set. Reachability requires OPENSSL_EXTRA, X509_V_FLAG_PARTIAL_CHAIN, and a peer-supplied intermediate; acceptance grants the certificate the integrity authority of a trusted anchor.

The record

CVE
CVE-2026-6091
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-295
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=5.7.4 <=5.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

wolfSSL · wolfSSLversion=5.7.4 <=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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation

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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