# CVSS Temporal and Environmental Scores

> The Base score is only the starting point. Temporal metrics lower it as facts emerge, such as a patch being released, and can only reduce the score. Environmental metrics let an organization re-score the flaw for its own systems by raising or lowering the importance of confidentiality, integrity, and availability and by overriding base metrics. Both are optional but produce a more honest number.

Source: https://ronutz.com/en/learn/cvss-temporal-and-environmental  
Updated: 2026-07-01  
Related tools: https://ronutz.com/en/tools/cvss-vector-decoder

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Most published CVSS scores are Base only, because the base is constant. But the framework was designed to be refined, and the two optional groups are where a score becomes specific to a moment in time and to a particular environment.

## Temporal metrics

The Temporal group has three metrics, each a multiplier that is at most 1.0, so the Temporal score can only be equal to or lower than the Base score:

- **Exploit Code Maturity (E)**: how ready an exploit is, from `U` Unproven through `P` Proof-of-Concept and `F` Functional to `H` High (reliable, widely available).
- **Remediation Level (RL)**: what fix exists, from `U` Unavailable through `W` Workaround and `T` Temporary Fix to `O` Official Fix.
- **Report Confidence (RC)**: how confirmed the flaw is, from `U` Unknown through `R` Reasonable to `C` Confirmed.

The Temporal score is simply the Base score multiplied by all three and rounded up:

`Temporal = Roundup(BaseScore x E x RL x RC)`

An official fix (`RL:O`) and an unproven exploit (`E:U`) pull a score down, which is the framework's way of saying a patched, hard-to-exploit flaw is less urgent than its raw base suggests.

## Environmental metrics

The Environmental group does two things. First, **Security Requirements** (`CR`, `IR`, `AR`) let you declare how much confidentiality, integrity, or availability matters for the affected system, at `L` Low, `M` Medium, or `H` High. A high integrity requirement raises the score of an integrity-affecting flaw on a system where integrity is critical. Second, **Modified Base Metrics** (`MAV`, `MAC`, `MPR`, `MUI`, `MS`, `MC`, `MI`, `MA`) let you override any base metric to reflect your deployment, for example changing Attack Vector from Network to Adjacent because the service is only reachable internally.

The environmental math mirrors the base math but uses the modified metrics and the requirements, and the modified impact sub-score is capped at `0.915`. The result is a score that reflects the flaw as it actually sits in your environment, which is often materially different from the headline number.

## When to use them

Temporal and Environmental scoring is optional but recommended when you are prioritising real work. A vendor cannot know your environment, so a Base score is deliberately worst-case. Re-scoring with the metrics you do know, an internal-only service, a compensating control, an available patch, frequently moves a flaw down a band and changes what you fix first.