NVD / CVE Program· CNA wolfSSL

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

Noroxi assessment

Priority: Monitor (action score 25/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: azl3 libical 3.0.10-1 on Azure Linux 3.0 Release Notes.

Low priority for now. Upgrade to azl3 libical 3.0.10-1 on Azure Linux 3.0 Release Notes or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 6.3 · v4.0—No exploit Fix available

EUVD-2026-87922

Published: Sep 27, 2026
Updated: Oct 2, 2026
EPSS: 0.1% · 2th percentile
CWE: CWE-295

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 25 / 40 · 6.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.1%

CISA SSVC decision

Exploitation: none
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · wolfSSL: 6.3; NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
wolfssl	wolfssl	cpe:2.3:a:wolfssl:wolfssl

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

wolfssl wolfsslup to 5.9.2 inclusive

Versions reported by the vendor

Affected version ranges reported by the assigning authority (wolfSSL). Independent of NVD's CPE analysis and usually ahead of it.

wolfSSL wolfSSL
- up to and including 5.9.2affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	wolfssl	from 0	—

Same product

wolfssl: all records

Other highest-scoring records for the same primary product.

CVE-2017-13099wolfSSL Bleichenbacher/ROBOT
60This week
CVE-2019-11873wolfSSL 4.0.0 has a Buffer Overflow in DoPreSharedKeys in tls13.c when a current identity size is greater than a client identity size.
42Plan
CVE-2017-2800A specially crafted x509 certificate can cause a single out of bounds byte overwrite in wolfSSL through 3.10.2 resulting in potential certif
42Plan

Published before and after this one in the same product

← EarlierCVE-2026-15442Sep 27, 2026 · Heap use-after-free on read during bidirectional (D)TLS shutdown
9Monitor
← EarlierCVE-2026-89102Sep 27, 2026 · OCSP stapling v2 multi accepts non-CA chain certificates as issuers
33Monitor
Later →CVE-2026-89134Sep 27, 2026 · Subject CN name-constraint check bypassed when non-DNS SAN present
25Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
azl3 libical 3.0.10-1 on Azure Linux 3.0	Release Notes	Microsoft (MSRC)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

wolfSSL/wolfsslPR 10687

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Jack Lloydfinder
PathDifffinder
Ben Smythfinder

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-5194171 days apartwolfSSL ECDSA Certificate Verification
37Monitor
CVE-2025-7395436 days apartDomain Name Validation Bypass with Apple Native Certificate Validation
36Monitor
CVE-2026-1131094 days apartX.509 trust-chain bypass in wolfSSL_X509_verify_cert() via untrusted intermediate anchoring
34Monitor
CVE-2026-5501170 days apartImproper Certificate Signature Verification in X.509 Chain Validation Allows Forged Leaf Certificates
34Monitor
CVE-2026-891020 days apartOCSP stapling v2 multi accepts non-CA chain certificates as issuers
33Monitor
CVE-2026-933020 days apartTrusted peer certificate match ignores public key, allowing forged CA clones
33Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: X

Weakness class (CWE)

CWE-295 · Improper Certificate Validation

CVSS vector

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

A certificate validation error is silently swallowed instead of terminating the connection. Often, code added for a test environment makes its way into production.

The bug in code

The whole CWE-295 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

kotlin

1override fun checkServerTrusted(chain: Array<X509Certificate>, type: String) {
2  // Left empty for the test environment
3}

Fixed

kotlin

1val client = OkHttpClient.Builder()
2  .certificatePinner(
3    CertificatePinner.Builder()
4      .add("api.sirius.example", "sha256/…")
5      .build()
6  ).build()

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log

Fix✗ → ✓Oct 3, 2026, 3:31 AM UTC
SSVC exploitation— → noneSep 29, 2026, 6:54 PM UTC

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References

github.com/wolfSSL/wolfssl/pull/10687

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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