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📖 Executive Summary

CVE-2026-45447 is a critical vulnerability in OpenSSL's PKCS#7 verification functionality.

The flaw exists within the PKCS7_verify() code path and can be triggered through a specially crafted PKCS#7 or S/MIME signed message containing a malformed ASN.1 structure.

Successful exploitation may result in:

• Heap corruption
• Application crashes
• Denial of Service (DoS)
• Potential Remote Code Execution (RCE)

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🎯 Vulnerability Information

Property	Value
CVE	CVE-2026-45447
Vendor	OpenSSL
Severity	Critical
CVSS v3.1	9.8
CWE	CWE-416
Vulnerability Type	Use-After-Free
Attack Vector	Remote
User Interaction	Required (message processing)
Authentication	None
Affected Component	PKCS7_verify()

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📸 Demo

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🔥 Technical Description

A malicious actor can craft a specially formed:

• PKCS#7 SignedData object
• S/MIME signed email
• CMS/PKI-related signed document

containing an empty ASN.1 SET inside:

SignedData.digestAlgorithms

During verification, OpenSSL incorrectly frees a BIO object while ownership is still assumed by the calling application.

Subsequent access results in a classic:

Heap Use-After-Free

condition.

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⚔️ Attack Flow

Attacker
    │
    ▼
Crafted PKCS#7 / S-MIME Message
    │
    ▼
Target Application
    │
    ▼
PKCS7_verify()
    │
    ▼
Unexpected BIO Free
    │
    ▼
Use-After-Free Triggered
    │
    ├── Application Crash
    ├── Memory Corruption
    └── Potential RCE

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💥 Impact

Confidentiality

Potential disclosure of sensitive memory contents.

Integrity

Heap corruption may allow attacker-controlled memory manipulation.

Availability

Application crashes and denial-of-service conditions.

Remote Code Execution

Possible depending on:
- Application architecture
- Heap layout
- Mitigations
- Exploitation primitives

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🖥️ Affected Versions

Branch	Status
OpenSSL 1.0.2	Affected
OpenSSL 1.1.1	Affected
OpenSSL 3.0.x	Affected
OpenSSL 3.4.x	Affected
OpenSSL 3.5.x	Affected
OpenSSL 3.6.x	Affected

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✅ Fixed Versions

Upgrade to vendor-patched releases provided by:

• OpenSSL
• Ubuntu
• Debian
• Red Hat
• SUSE
• Oracle Linux
• Amazon Linux

Always verify package versions from your operating system vendor.

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📊 CVSS Breakdown

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

Metric	Value
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	Required
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High

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🎯 Potentially Affected Products

Applications using OpenSSL's PKCS#7 verification APIs:

Email Infrastructure

• Secure Email Gateways
• S/MIME Mail Servers
• Exchange Integrations
• Mail Security Appliances

PKI Platforms

• Certificate Validation Services
• Trust Management Systems
• Signing Gateways

Enterprise Software

• Document Signing Platforms
• Secure Messaging Systems
• Internal PKI Solutions

Custom Applications

Any software directly invoking:

PKCS7_verify()

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🔍 Detection & Hunting

Crash Indicators

Segmentation fault
SIGSEGV
SIGABRT
Double free
Heap corruption

Linux Logs

journalctl -xe

dmesg | grep segfault

grep -Ri "openssl" /var/log/

Application Logs

Look for:

PKCS7_verify failed
BIO error
ASN1 parsing failure
SMIME verification failure
Heap corruption detected

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🛡️ Mitigation

Immediate Actions

• Patch OpenSSL
• Inventory PKCS#7 consumers
• Restrict untrusted signed content
• Monitor crashes
• Enable EDR monitoring

Short-Term Actions

• Review email security infrastructure
• Inspect S/MIME processing pipelines
• Validate certificate verification workflows

Long-Term Actions

• Implement secure dependency management
• Automate OpenSSL updates
• Establish vulnerability scanning processes

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🔬 Reproduction Overview

1. Create malformed PKCS#7 structure
2. Embed empty ASN.1 SET
3. Deliver to target application
4. Trigger PKCS7_verify()
5. Observe heap corruption

⚠️ This repository intentionally excludes weaponized exploit code.

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📈 Threat Landscape

High Risk Targets

• Government email systems
• Financial institutions
• Enterprise mail gateways
• PKI infrastructures
• Certificate validation services

Why It Matters

OpenSSL is one of the most widely deployed cryptographic libraries worldwide.

A vulnerability affecting signature validation routines may impact:

• Email security
• Digital signatures
• Enterprise trust systems
• Secure document workflows

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📚 References

Official Advisories

• OpenSSL Security Advisory
• NIST NVD
• Ubuntu Security Notice
• Debian Security Tracker
• Red Hat Security Advisory

Standards

• RFC 2315 (PKCS #7)
• RFC 5652 (CMS)
• RFC 8551 (S/MIME)

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📁 Repository Structure

CVE-2026-45447/
│
├── README.md
│
├── assets/
│   ├── CVE-2026-45447.png
│   └── screenshots/
│
├── advisory/
│   ├── technical-analysis.md
│   ├── timeline.md
│   └── impact-assessment.md
│
├── detection/
│   ├── sigma/
│   ├── yara/
│   └── hunting-guide.md
│
├── iocs/
│   └── indicators.md
│
└── references/
    └── links.md

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⚠️ Disclaimer

This repository is intended exclusively for:

• Vulnerability research
• Defensive security
• Threat intelligence
• Incident response
• Security awareness

The information contained herein must be used only in authorized environments and in accordance with applicable laws and regulations.

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