Cyber Resilience

CVE-2026-50269

Aiohttp ≤ 3.14.0

Published
22 June 2026
Modified
26 June 2026
Patch / advisory
View advisory
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:N/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 0.0030 23th percentile
Risk Priority 33 floored blend · peak EPSS

Summary

CVE-2026-50269 is a low-severity CRLF Injection (CWE-93) vulnerability in Aiohttp Aiohttp. Its CVSS base score is 2.7 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique Content Injection (T1659); ranked at the 23th 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 SI-10 (Information Input Validation) and SI-15 (Information Output Filtering) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.0, attacker-controlled input included into multipart/payload headers can be used to modify a request to inject additional headers or similar. In the unlikely situation that an application…

more

is passing user-controlled strings into MultipartWriter.append(headers=...) or Payload.headers, then an attacker may be able to modify the request to inject headers or change the contents of the request. This vulnerability is fixed in 3.14.0.

CWE(s)
CWE-93CWE-113

Related Threats

MITRE ATT&CK Enterprise Techniques

T1659 Content Injection Initial Access
Adversaries may gain access and continuously communicate with victims by injecting malicious content into systems through online network traffic.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-34519Same product: Aiohttp Aiohttp
CVE-2026-34520Same product: Aiohttp Aiohttp
CVE-2026-34514Same product: Aiohttp Aiohttp
CVE-2023-49082Same product: Aiohttp Aiohttp
CVE-2023-37276Same product: Aiohttp Aiohttp
CVE-2025-69225Same product: Aiohttp Aiohttp
CVE-2024-52304Same product: Aiohttp Aiohttp
CVE-2023-47627Same product: Aiohttp Aiohttp
CVE-2026-34515Same product: Aiohttp Aiohttp
CVE-2023-47641Same product: Aiohttp Aiohttp

Affected Assets

aiohttp
aiohttp
≤ 3.14.0

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)
  • V3.4.2
  • V4.1.3
  • V1.3.6
  • V4.2.3

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

Input validation directly stops untrusted data containing CRLF sequences from reaching the component that treats CRLF as a delimiter.

SI-15 Information Output Filtering good match

Output filtering can neutralize CRLF sequences before they reach HTTP response headers.

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.PS-06 mostly match
prevents

Secure SDLC practices directly require input neutralization and validation to block CRLF injection.

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 CRLF flaws but does not itself implement the neutralization.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and output encoding that directly prevents CRLF injection.

A.8.26 Application security requirements partial match
prevents

Application security requirements include rules for neutralizing special characters such as CRLF in inputs.

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

Secure architecture principles encourage safe handling of untrusted data but do not prescribe specific CRLF controls.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly require neutralization of CRLF sequences, fully addressing this weakness.

A.8.15 Logging none match
none

Logging of HTTP traffic can record header-splitting attempts, aiding detection and forensics.

References