CVE-2026-43377

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: Don't log keys in SMB3 signing and encryption key generation When KSMBD_DEBUG_AUTH logging is enabled, generate_smb3signingkey() and generate_smb3encryptionkey() log the session, signing, encryption, and decryption key bytes. Remove the logs to avoid exposing credentials.

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Linux Kernel (ksmbd module) with KSMBD_DEBUG_AUTH enabled

PoC / Exploit Code

⚠ For Security Research Only

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

python

import subprocess
import re

# PoC Concept: Check if ksmbd is logging keys in dmesg
# This script simulates the verification of the vulnerability.

def check_logs_for_key_leak():
    try:
        # Read kernel logs
        result = subprocess.run(['dmesg'], capture_output=True, text=True)
        logs = result.stdout
        
        # Pattern to look for (based on vulnerable code description)
        # Searching for explicit key logging patterns
        patterns = [
            r'session key:\s+[0-9a-fA-F]+',
            r'signing key:\s+[0-9a-fA-F]+',
            r'encryption key:\s+[0-9a-fA-F]+'
        ]
        
        found = False
        for pattern in patterns:
            if re.search(pattern, logs):
                print(f"[!] Potential key leak found in logs matching pattern: {pattern}")
                found = True
                
        if not found:
            print("[-] No explicit key leaks found in current dmesg output.")
            print("[Note]: Vulnerability is triggered when KSMBD_DEBUG_AUTH is enabled during SMB operations.")
            
    except Exception as e:
        print(f"Error running check: {e}")

if __name__ == "__main__":
    print("CVE-2026-43377 PoC Checker (ksmbd key leak)")
    check_logs_for_key_leak()

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43377
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43377
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43377/
[4] VulDB https://vuldb.com/cve/CVE-2026-43377
[5] https://git.kernel.org/stable/c/3fe2d9ec166b7df9a8df6c0fdcfc210572e27e3f
[6] https://git.kernel.org/stable/c/407cc37c21d51f9b9d4d20204b04890880cfa6ae
[7] https://git.kernel.org/stable/c/4084ed720d7d5f4e975c9e4a6267a552dad3b24a
[8] https://git.kernel.org/stable/c/441336115df26b966575de56daf7107ed474faed
[9] https://git.kernel.org/stable/c/c6b01b997a2094969e315f1ebfc1d64b8ae2163d
[10] https://git.kernel.org/stable/c/fec5c70b82af3f59f15bb984df94e5ad1fccfb1e

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43377", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T15:16:48.877", "lastModified": "2026-05-11T08:16:12.203", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: Don't log keys in SMB3 signing and encryption key generation\n\nWhen KSMBD_DEBUG_AUTH logging is enabled, generate_smb3signingkey() and\ngenerate_smb3encryptionkey() log the session, signing, encryption, and\ndecryption key bytes. Remove the logs to avoid exposing credentials."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "references": [{"url": "https://git.kernel.org/stable/c/3fe2d9ec166b7df9a8df6c0fdcfc210572e27e3f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/407cc37c21d51f9b9d4d20204b04890880cfa6ae", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/4084ed720d7d5f4e975c9e4a6267a552dad3b24a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/441336115df26b966575de56daf7107ed474faed", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/c6b01b997a2094969e315f1ebfc1d64b8ae2163d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/fec5c70b82af3f59f15bb984df94e5ad1fccfb1e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}]}}