CVE-2026-59881: CWE-20: Improper Input Validation in aio-libs aiohttp
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory consumption. This issue is fixed in version 3.14.2.
AI Analysis
Technical Summary
CVE-2026-59881 is an improper input validation vulnerability (CWE-20) in the aiohttp asynchronous HTTP client/server framework for Python. Specifically, the WebSocket client accepts and decompresses frames with the RSV1 bit set without verifying that the permessage-deflate extension was negotiated. This flaw allows a malicious server to cause unexpected resource consumption on the client side. The vulnerability affects aiohttp versions prior to 3.14.2 and is resolved in version 3.14.2.
Potential Impact
Exploitation of this vulnerability can cause unexpected CPU and memory consumption on clients using vulnerable aiohttp versions, potentially leading to denial of service or degraded performance. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade aiohttp to version 3.14.2 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is documented.
CVE-2026-59881: CWE-20: Improper Input Validation in aio-libs aiohttp
Description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory consumption. This issue is fixed in version 3.14.2.
CVSS v4.0
Score 6.9medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-59881 is an improper input validation vulnerability (CWE-20) in the aiohttp asynchronous HTTP client/server framework for Python. Specifically, the WebSocket client accepts and decompresses frames with the RSV1 bit set without verifying that the permessage-deflate extension was negotiated. This flaw allows a malicious server to cause unexpected resource consumption on the client side. The vulnerability affects aiohttp versions prior to 3.14.2 and is resolved in version 3.14.2.
Potential Impact
Exploitation of this vulnerability can cause unexpected CPU and memory consumption on clients using vulnerable aiohttp versions, potentially leading to denial of service or degraded performance. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade aiohttp to version 3.14.2 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is documented.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-07T16:40:07.982Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a6b8fab9c2644c7f873173f
Added to database: 07/30/2026, 17:53:47 UTC
Last enriched: 07/30/2026, 18:07:51 UTC
Last updated: 07/31/2026, 02:37:09 UTC
Views: 7
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