CVE-2026-6450

CRL validation bypass via ignored critical extensions

Published Jun 25, 2026 · Updated Jun 25, 2026

Improper CRL validation in wolfSSL 4.3.0 through 5.9.1 allows attackers to bypass extension enforcement via a crafted CRL. ParseCRL_Extensions parses an unrecognized CRL extension but fails to reject it when its critical flag is set. Reachability requires CRL support and a crafted CRL bearing a signature trusted by the consuming application, which then treats unsupported CRL semantics as valid.

CVSS severity1.0
Low
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper CRL validation in wolfSSL 4.3.0 through 5.9.1 allows attackers to bypass extension enforcement via a crafted CRL. ParseCRL_Extensions parses an unrecognized CRL extension but fails to reject it when its critical flag is set. Reachability requires CRL support and a crafted CRL bearing a signature trusted by the consuming application, which then treats unsupported CRL semantics as valid.

The record

CVE
CVE-2026-6450
Published
Jun 25, 2026
Updated
Jun 25, 2026
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-295
Attack vector
adjacent
Privileges
Unavailable

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?

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  1. Affected versionversion=4.3.0 <=5.9.1

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesUnavailable in this record.

What is affected?

wolfSSL · wolfSSLversion=4.3.0 <=5.9.1

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
1.0wolfSSL Inc.CVSS:4.0/AV:A/AC:H/AT:P/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
PrivilegesUnavailable
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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