Executive Summary
A vulnerability was found in priyankark a11y-mcp up to 1.0.5. This vulnerability affects the function A11yServer of the file src/index.js. The manipulation results in server-side request forgery. The attack must be initiated from a local position. The exploit has been made public and could be used. This product operates on a rolling release basis, ensuring continuous delivery. Consequently, there are no version details for either affected or updated releases. Upgrading to version 1.0.6 is able to resolve this issue. The patch is identified as e3e11c9e8482bd06b82fd9fced67be4856f0dffc. It is recommended to upgrade the affected component. The vendor acknowledged the issue but provides additional context for the CVSS rating: "a11y-mcp is a local stdio MCP server - it has no HTTP endpoint and is not network-accessible. The caller is always the local user or an LLM acting on their behalf with user approval."
Quantitative Risk Analysis
Attack Vector Profile
The payload vectors broken down by magnitude impact and ease-of-deployment factor mapping.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:LWhat This Means For Your System
Each point below is derived directly from this CVE's CVSS v3.1 vector — not editorial opinion.
Requires local system access; remote exploitation is not possible.
No special preconditions — the attack is reliably repeatable.
A basic authenticated account is sufficient to trigger this.
No user interaction required — the attacker acts autonomously.
Successful exploitation causes: partial information disclosure, limited data modification, partial service degradation.
OsVault Risk Score Methodology
The OsVault composite score is a 5-layer non-linear engine — not a simple weighted average. Each input signal is transformed through mathematically appropriate curves before blending, ensuring that exploitability context overrides raw severity when warranted.
Layer 1 (Technical): CVSS is mapped through a piecewise exponential curve with 4 bands (LOW 0–20, MEDIUM 20–55, HIGH 55–85, CRITICAL 85–100), then multiplied by full CVSS vector decomposition factors for Attack Vector, Complexity, Privileges, and User Interaction.
Layer 2 (Threat): Raw EPSS is passed through a logistic sigmoid (k=40, midpoint=0.05) to maximize discrimination in the decision-relevant range. The result is added to an exploit maturity tier base score (Weaponized: 85, Functional: 55, PoC: 40, Unproven: 18).
Layer 3 (KEV Floor):Any CVE in CISA's catalog receives a hard minimum of 93.0 (Functional) or 97.0 (Weaponized). This ensures confirmed exploitation is never buried by low CVSS scores.
Scores ≥70: patch immediately. 40–69: schedule within current sprint. Below 40: standard maintenance cycle.
Remediation Commands
Commands to update each affected package identified in this advisory. Verify the target release explicitly addresses this CVE in the upstream changelog before deploying to production.
npm install a11y-mcp@latest