CVE-2026-54275: CWE-297: Improper Validation of Certificate with Host Mismatch in aio-libs aiohttp
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, the server_hostname TLS SNI check can be bypassed when an existing connection is reused. If an application makes multiple requests to the same domain, but with different per-request server_hostname parameters, then the later calls may succeed by reusing the existing connection when they should have been rejected due to the TLS SNI check. This vulnerability is fixed in 3.14.1.
AI Analysis
Technical Summary
CVE-2026-54275 affects aiohttp, an asynchronous HTTP client/server framework for Python. The vulnerability involves improper validation of TLS server certificates with host mismatches (CWE-297). Specifically, when an existing connection is reused, the server_hostname TLS SNI check can be bypassed if multiple requests to the same domain specify different server_hostname parameters. This can cause later requests to succeed when they should be rejected due to TLS SNI mismatch. The flaw is addressed in aiohttp version 3.14.1.
Potential Impact
The vulnerability could allow an attacker to bypass TLS server hostname verification when connections are reused, potentially undermining the security guarantees of TLS SNI checks. However, the CVSS score is low (2.7), indicating limited impact and exploitability. There are no known exploits in the wild.
Mitigation Recommendations
Upgrade aiohttp to version 3.14.1 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is indicated.
CVE-2026-54275: CWE-297: Improper Validation of Certificate with Host Mismatch in aio-libs aiohttp
Description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, the server_hostname TLS SNI check can be bypassed when an existing connection is reused. If an application makes multiple requests to the same domain, but with different per-request server_hostname parameters, then the later calls may succeed by reusing the existing connection when they should have been rejected due to the TLS SNI check. This vulnerability is fixed in 3.14.1.
CVSS v4.0
Score 2.7low
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-54275 affects aiohttp, an asynchronous HTTP client/server framework for Python. The vulnerability involves improper validation of TLS server certificates with host mismatches (CWE-297). Specifically, when an existing connection is reused, the server_hostname TLS SNI check can be bypassed if multiple requests to the same domain specify different server_hostname parameters. This can cause later requests to succeed when they should be rejected due to TLS SNI mismatch. The flaw is addressed in aiohttp version 3.14.1.
Potential Impact
The vulnerability could allow an attacker to bypass TLS server hostname verification when connections are reused, potentially undermining the security guarantees of TLS SNI checks. However, the CVSS score is low (2.7), indicating limited impact and exploitability. There are no known exploits in the wild.
Mitigation Recommendations
Upgrade aiohttp to version 3.14.1 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-12T17:13:32.280Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a39735beed863c81e39625a
Added to database: 06/22/2026, 17:39:39 UTC
Last enriched: 06/22/2026, 17:55:42 UTC
Last updated: 06/22/2026, 19:09:21 UTC
Views: 2
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