EUVD-2026-44939Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/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
Unauthenticated code execution (PR:N) via a delivered file that a user/process must load (UI:R), low complexity, full C/I/A impact within the host process (scope unchanged).
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/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
Lifecycle Timeline
4DescriptionCVE.org
Prompty is a markdown file format (.prompty) for LLM prompts. From 2.0.0-alpha.1 until 2.0.0-beta.3, the @prompty/core TypeScript loader in runtime/typescript/packages/core/src/core/loader.ts used gray-matter without overriding executable js and javascript frontmatter engines, allowing an attacker-controlled .prompty file with ---js frontmatter to execute arbitrary JavaScript during prompt loading. This issue is fixed in version 2.0.0-beta.3.
AnalysisAI
Arbitrary JavaScript execution in Microsoft's @prompty/core TypeScript loader (2.0.0-alpha.1 through 2.0.0-beta.2) allows an attacker who supplies a crafted .prompty file to run code during prompt loading. The loader passed .prompty markdown to gray-matter without disabling its executable 'js'/'javascript' frontmatter engines, so a '---js' frontmatter block is evaluated as Node.js at parse time. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the target application load an attacker-controlled .prompty file through the @prompty/core TypeScript loader (versions 2.0.0-alpha.1 to 2.0.0-beta.2). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | Signals are largely consistent toward high but not maximum urgency. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker publishes or submits a .prompty file (e.g. via a prompt marketplace, shared repository, plugin, or user upload) containing a '---js' frontmatter block such as require('node:fs').writeFileSync(...) or a reverse-shell payload. … |
| Remediation | Vendor-released patch: upgrade @prompty/core (and dependent @prompty/* packages) to 2.0.0-beta.3 or later, which registers hardened js/javascript gray-matter engines that throw instead of evaluating executable frontmatter. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all applications and services using @prompty/core versions 2.0.0-alpha.1 through 2.0.0-beta.2 via dependency auditing tools. …
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Same weakness CWE-94 – Code Injection
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External POC / Exploit Code
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