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CVE-2026-89133— NameConstraints not enforced across unconstrained intermediate CA

Quick assessment

Affected
wolfSSL wolfSSL
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

wolfSSL 5.9.2 及更早版本中存在一个 X.509 证书验证逻辑缺陷。当在带有名称约束（NameConstraints）的中间证书 CA 与叶子证书之间存在一个无约束的 CA 层级时，该漏洞导致 wolfSSL 无法正确强制执行 NameConstraints 扩展。由于链遍历（chain-walking）状态机中存在一个错误——在遇到没有 NameConstraints 的中间证书时会重置验证状态，从而使 wolfSSL 错误地接受了本不应被允许覆盖的主机名对应的证书，进而绕过了密码学委托控制。此缺陷存

CVSS 6.3 · Medium EPSS 0.23% · P12
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I. Basic Information for CVE-2026-89133

Vulnerability Information
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Vulnerability Title
NameConstraints not enforced across unconstrained intermediate CA
Source: CVE Program / CVE List V5
Vulnerability Description
wolfSSL versions 5.9.2 and earlier contain a flaw in the X.509 certificate validation logic where it fails to properly enforce NameConstraints extensions when there is an unconstrained CA tier between a name-constrained intermediate CA and the leaf certificate. wolfSSL incorrectly accepted certificates for hostnames they shouldn't be allowed to cover, due to a chain-walking state-machine bug that resets the validation state when encountering an intermediate without NameConstraints, thereby bypassing cryptographic delegation controls. This defect exists in the default build configuration that makes use of certificates where name constraint extensions are used. Thanks to Jack Lloyd, PathDiff, and Ben Smyth for reporting the issue.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
证书验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
wolfSSL wolfSSL 0 ~ 5.9.2 -

II. Public POCs for CVE-2026-89133

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III. Intelligence Information for CVE-2026-89133

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Other References for CVE-2026-89133 (1)

Same Patch Batch · wolfSSL · 2026-09-27 · 11 CVEs total

CVE-2026-93302 8.3 HIGH Trusted peer certificate match ignores public key, allowing forged CA clones
CVE-2026-89136 8.3 HIGH Client accepts unsolicited RawPublicKey server certificate type
CVE-2026-89102 8.3 HIGH OCSP stapling v2 multi accepts non-CA chain certificates as issuers
CVE-2026-93304 6.3 MEDIUM (D)TLS 1.2 client accepts early ChangeCipherSpec before ClientKeyExchange
CVE-2026-89134 6.3 MEDIUM Subject CN name-constraint check bypassed when non-DNS SAN present
CVE-2026-89135 6.3 MEDIUM Failed X509_verify_cert leaves unverified CA in shared CertManager
CVE-2026-15442 2.3 LOW Heap use-after-free on read during bidirectional (D)TLS shutdown
CVE-2026-94418 2.3 LOW Signature failure masked by date error under WOLFSSL_SMALL_CERT_VERIFY
CVE-2026-94419 2.3 LOW Client session cache reference poisoning allows resumption with wrong server
CVE-2026-94417 2.3 LOW CRL check skipped when OCSP enabled and certificate has no OCSP URL

IV. Related Vulnerabilities

Same product: wolfSSL
Same vendor: wolfSSL
Same weakness: CWE-295

V. Comments for CVE-2026-89133

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