CVE-2026-43384

Description

In the Linux kernel, the following vulnerability has been resolved: net/tcp-ao: Fix MAC comparison to be constant-time To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.

CVSS Details

CVSS Score

9.8

Severity

CRITICAL

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Linux Kernel（包含特定提交前的版本）

PoC / Exploit Code

⚠ For Security Research Only

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

python

#!/usr/bin/env python3
# Conceptual PoC for Timing Attack on MAC comparison
import time
def vulnerable_mac_compare(mac1, mac2):
    """
    Simulates a vulnerable non-constant time comparison.
    Returns False as soon as a mismatch is found.
    """
    if len(mac1) != len(mac2):
        return False
    for i in range(len(mac1)):
        if mac1[i] != mac2[i]:
            return False  # Early return leaks timing info
    return True

def measure_time(target_mac, guess_mac):
    start = time.perf_counter_ns()
    vulnerable_mac_compare(target_mac, guess_mac)
    end = time.perf_counter_ns()
    return end - start

if __name__ == "__main__":
    TARGET = "SECRET_KEY_12345"
    print("[*] Starting timing analysis...")
    # Simulation: Attacker guesses the first byte
    for char_code in range(32, 127):
        guess = chr(char_code) + "A" * (len(TARGET) - 1)
        duration = measure_time(TARGET, guess)
        # In a real attack, the correct byte usually takes slightly longer
        # because it proceeds to check the next byte.
        print(f"Guess: {guess} | Time: {duration} ns")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43384
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43384
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43384/
[4] VulDB https://vuldb.com/cve/CVE-2026-43384
[5] https://git.kernel.org/stable/c/080b0e210088296dd50d6637c06c1db14246adfe
[6] https://git.kernel.org/stable/c/67edfec516d30d3e62925c397be4a1e5185802fc
[7] https://git.kernel.org/stable/c/8be6ed64966da48b6c4726918f106c18742a5125
[8] https://git.kernel.org/stable/c/a269cbdc442f8658bca35383e34b9d0b0ff95a1c

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43384", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T15:16:49.720", "lastModified": "2026-05-11T08:16:12.580", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tcp-ao: Fix MAC comparison to be constant-time\n\nTo prevent timing attacks, MACs need to be compared in constant\ntime.  Use the appropriate helper function for this."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "references": [{"url": "https://git.kernel.org/stable/c/080b0e210088296dd50d6637c06c1db14246adfe", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/67edfec516d30d3e62925c397be4a1e5185802fc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/8be6ed64966da48b6c4726918f106c18742a5125", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/a269cbdc442f8658bca35383e34b9d0b0ff95a1c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}]}}