Security Digest · Vulnerability record
CVE-2025-54136: Cursor's Modification of MCP Server Definitions Bypasses Manual Re-approvals
Cursor is a code editor built for programming with AI.
CVSS 7.2 High EPSS 28.3% · p98 Most can relax
Should you act?
High exploit likelihood
EPSS ranks it in the top 5% of all CVEs for likely exploitation in the next 30 days. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 28.3%, percentile 98: FIRST’s model estimates a 28.3% chance of exploitation activity in the next 30 days, higher than 98% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Needs an account (high (admin)). Exposure depends on who can log in.
- Editorial verdict: Most can relax. Cursor CurXecute: Prompt Injection to RCE via mcp.json — Cursor auto-updates and both bugs were fixed by mid-2025; the lasting takeaway is to treat any agent that can write its own tool config as a code-execution path.
What it is
Cursor is a code editor built for programming with AI. In versions 1.2.4 and below, attackers can achieve remote and persistent code execution by modifying an already trusted MCP configuration file inside a shared GitHub repository or editing the file locally on the target's machine. Once a collaborator accepts a harmless MCP, the attacker can silently swap it for a malicious command (e.g., calc.exe) without triggering any warning or re-prompt. If an attacker has write permissions on a user's active branches of a source repository that contains existing MCP servers the user has previously approved, or allows an attacker has arbitrary file-write locally, the attacker can achieve arbitrary code execution. This is fixed in version 1.3.
Weakness type: CWE-78.
Product: cursor cursor · Assigned by: GitHub_M · Published: 2025-08-01
Affected and fixed versions
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| cursor | cursor | < 1.3 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 7.2 High | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: high (admin)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable no, technical impact total.
- FIRST EPSS (model of 2026-10-21): 28.26% probability of exploitation activity in the next 30 days; percentile 98.
Timeline
- — CVE record published by GitHub_M
- — erroneo.us brief: Cursor CurXecute: Prompt Injection to RCE via mcp.json
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- CVE.org record CVE-2025-54136 cve.org
- NVD entry CVE-2025-54136 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com