Cyber Resilience

CVE-2026-54275

Aiohttp ≤ 3.14.1

Published
22 June 2026
Modified
26 June 2026
CVSS Score v4 2.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/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
EPSS Score 0.0027 18th percentile
Risk Priority 32 floored blend · peak EPSS

Summary

CVE-2026-54275 is a low-severity Improper Validation of Certificate with Host Mismatch (CWE-297) vulnerability in Aiohttp Aiohttp. Its CVSS base score is 2.7 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 18th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-23 (Session Authenticity) and SC-8 (Transmission Confidentiality and Integrity) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-297

Related Threats

MITRE ATT&CK Enterprise Techniques

T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
T1557.001 Name Resolution Poisoning and SMB Relay Credential Access
By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.
attack.mitre.org →
T1557.002 ARP Cache Poisoning Credential Access
Adversaries may poison Address Resolution Protocol (ARP) caches to position themselves between the communication of two or more networked devices.
attack.mitre.org →
T1557.003 DHCP Spoofing Credential Access
Adversaries may redirect network traffic to adversary-owned systems by spoofing Dynamic Host Configuration Protocol (DHCP) traffic and acting as a malicious DHCP server on the victim network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-47265Same product: Aiohttp Aiohttp
CVE-2023-37276Same product: Aiohttp Aiohttp
CVE-2026-34516Same product: Aiohttp Aiohttp
CVE-2026-34518Same product: Aiohttp Aiohttp
CVE-2026-34525Same product: Aiohttp Aiohttp
CVE-2026-34519Same product: Aiohttp Aiohttp
CVE-2026-54273Same product: Aiohttp Aiohttp
CVE-2026-54280Same product: Aiohttp Aiohttp
CVE-2026-54274Same product: Aiohttp Aiohttp
CVE-2025-69225Same product: Aiohttp Aiohttp

Affected Assets

aiohttp
aiohttp
≤ 3.14.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V17.2.8

Mitigating Controls (NIST 800-53 r5) AI

SC-23 Session Authenticity good match

Protecting session authenticity structurally requires proper certificate validation to bind the presented certificate to the intended host.

SC-8 Transmission Confidentiality and Integrity good match

Requiring confidentiality and integrity of transmitted data necessitates correct TLS certificate validation with host-name checking.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles require correct implementation of certificate validation (including hostname matching) when cryptography is used.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.DS-02 mostly match
prevents

Protecting data-in-transit integrity depends on proper certificate validation to prevent MITM.

PR.PS-06 mostly match
prevents

Secure development practices include coding correct certificate validation logic.

PR.AA-03 partial match
prevents

Server/service authentication via certificates directly requires correct host validation.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect missing certificate validation and host-mismatch checks.

A.8.20 Networks security partial match
degrades

Network security controls include certificate validation and host-name verification to prevent man-in-the-middle attacks.

A.8.21 Security of network services partial match
degrades

Security of network services requires proper TLS configuration and certificate validation for service endpoints.

A.8.24 Use of cryptography partial match
prevents

Use of cryptography mandates correct implementation of certificate validation and hostname verification.

A.8.26 Application security requirements partial match
prevents

Application security requirements include secure communication and certificate validation for external services.

A.8.27 Secure system architecture and engineering principles partial match
mitigates

Secure system architecture principles require proper certificate validation to protect communications.

References