CVSS Score (v3.1 Vector String) Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching cvss score (v3.1 vector string), ported and verified for Python. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# CVSS Score (v3.1 Vector String)
# ReDoS-safe | RegexVault — Security > Network Security

import re

cvss_score_v31_vector_string_pattern = re.compile(r'^CVSS:3\.[01]/AV:[NALP]/AC:[LH]/PR:[NLH]/UI:[NR]/S:[UC]/C:[NLH]/I:[NLH]/A:[NLH]$')

def validate_cvss_score_v31_vector_string(value: str) -> bool:
    return bool(cvss_score_v31_vector_string_pattern.fullmatch(value))

# Example
print(validate_cvss_score_v31_vector_string("CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Security > Network Security category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

CVSS v3.1 base metrics: AV (Attack Vector: N/A/L/P), AC (Attack Complexity: L/H), PR (Privileges Required: N/L/H), UI (User Interaction: N/R), S (Scope: U/C), C/I/A (Impact: N/L/H). Log4Shell = CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H = 10.0 Critical.