Security Vulnerability Report
中文
CVE-2026-4727 CVSS 7.5 HIGH

CVE-2026-4727

Published: 2026-03-24 13:16:09
Last Modified: 2026-04-13 15:17:45

Description

Denial-of-service in the Libraries component in NSS. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

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:N/A:H

Configurations (Affected Products)

cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:* - VULNERABLE
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:* - VULNERABLE
Firefox < 149
Thunderbird < 149

PoC / Exploit Code

⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
import socket import sys # Conceptual PoC for CVE-2026-4727 # This script demonstrates how to send a payload to a target service. # The specific payload bytes to trigger the NSS crash would need to be # derived from the specific bug analysis or patch diff. def send_exploit(target_ip, target_port): try: print(f"[*] Connecting to {target_ip}:{target_port}...") s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(5) s.connect((target_ip, target_port)) # Placeholder for the malicious payload. # In a real scenario, this would be the specific TLS handshake # or data packet that causes NSS to crash. payload = b"\x00\x00\x00\x00" print("[*] Sending payload...") s.send(payload) # Try to receive response to confirm connection state response = s.recv(1024) print("[+] Received response, service might be up.") except Exception as e: print(f"[!] Connection failed or service crashed: {e}") finally: s.close() if __name__ == "__main__": if len(sys.argv) != 3: print("Usage: python poc.py <ip> <port>") sys.exit(1) TARGET_IP = sys.argv[1] TARGET_PORT = int(sys.argv[2]) send_exploit(TARGET_IP, TARGET_PORT)

References

Raw JSON Data

JSON
{"cve": {"id": "CVE-2026-4727", "sourceIdentifier": "[email protected]", "published": "2026-03-24T13:16:08.570", "lastModified": "2026-04-13T15:17:45.243", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "Denial-of-service in the Libraries component in NSS. This vulnerability was fixed in Firefox 149 and Thunderbird 149."}, {"lang": "es", "value": "Denegación de servicio en el componente de Bibliotecas en NSS. Esta vulnerabilidad afecta a Firefox &lt; 149 y Thunderbird &lt; 149."}], "metrics": {"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:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "versionEndExcluding": "149.0", "matchCriteriaId": "02F2B82F-E997-4D5F-BBB0-237E4962555B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*", "versionEndExcluding": "149.0", "matchCriteriaId": "40FE4697-89F1-46F6-8E28-41883647583B"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2008112", "source": "[email protected]", "tags": ["Permissions Required"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-20/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-23/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}