Cyber Resilience

CVE-2026-6019

Python ≤ 3.13.14

Public PoC
Published
22 April 2026
Modified
27 July 2026
Patch / advisory
View advisory
CVSS Score v4 2.1
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/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 0.0023 14th percentile
Risk Priority 15 floored blend · peak EPSS

Summary

CVE-2026-6019 is a low-severity Improper Neutralization of Escape, Meta, or Control Sequences (CWE-150) vulnerability in Python Python. Its CVSS base score is 2.1 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 14th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

http.cookies.Morsel.js_output() returns an inline <script> snippet and only escapes " for JavaScript string context. It does not neutralize the HTML parser-sensitive sequence </script> inside the generated script element. Mitigation base64-encodes the cookie value to disallow escaping using cookie value.

CWE(s)
CWE-150CWE-116

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

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 →
T1059.007 JavaScript Execution
Adversaries may abuse various implementations of JavaScript for execution.
attack.mitre.org →
Why these techniques?

Vulnerability enables XSS via improper neutralization in cookie-to-JS output, directly facilitating exploitation of public-facing web apps and arbitrary JavaScript execution.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-3644Same product: Python Python
CVE-2026-4360Same product: Python Python
CVE-2025-6075Same product: Python Python
CVE-2026-7210Same product: Python Python
CVE-2024-7592Same product: Python Python
CVE-2023-40217Same product: Python Python
CVE-2025-13462Same product: Python Python
CVE-2024-9287Same product: Python Python
CVE-2026-4519Same product: Python Python
CVE-2025-12084Same product: Python Python

Affected Assets

python
python
3.15.0 · ≤ 3.13.14 · 3.14.0 — 3.14.4

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-10 Information Input Validation
  • SA-15 Development Process, Standards, and Tools
  • SI-2 Flaw Remediation
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.2
  • V1.2.1
  • V1.2.3
  • V1.2.10

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match
prevent

Directly requires sanitization/encoding of untrusted cookie values before they reach js_output(), blocking the </script> sequence that only "-escaping permits.

SA-15 Development Process, Standards, and Tools partial match
prevent

Mandates use of secure development standards and output-encoding libraries that would have required complete HTML/JS context-aware escaping inside Morsel.js_output().

SI-2 Flaw Remediation partial match
prevent

Requires prompt application of patches that replace the incomplete escaping logic in http.cookies with context-safe encoding or base64 handling.

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 escaping to prevent this class of flaw.

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.8.28 Secure coding mostly match
prevents

Secure coding standards explicitly require correct output encoding and escaping to preserve message structure.

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

Security testing can detect the weakness but does not itself implement neutralization.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and output encoding that directly neutralizes escape/meta sequences.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for controls against injection and malformed input sequences.

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

Secure architecture principles reduce attack surface but do not prescribe specific neutralization techniques.

References