{"id":"CVE-2026-73299","aliases":["EUVD-2026-57382","GHSA-w28w-gp39-m4p6"],"status":"published","title":"Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer","description":"Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 0.1.5 and 2.0.0-beta.5, the TypeScript Nunjucks renderer evaluated untrusted .prompty template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process. This issue is fixed in versions 0.1.5 and 2.0.0-beta.5.","severity":{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.01784,"percentile":0.78479,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1336","CWE-94"],"published":"2026-07-24T16:23:59Z","modified":"2026-10-28T02:30:49Z","fixes":[{"ecosystem":"npm","package":"@prompty/core","fixed_in":["0.1.5","2.0.0-beta.5"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@prompty/core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.1.4"},{"fixed":"0.1.5"}]}]},{"source":"ghsa","ecosystem":"npm","package":"@prompty/core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.0.0-alpha.1"},{"last_affected":"2.0.0-beta.4"},{"fixed":"2.0.0-beta.5"}]}]},{"source":"osv","ecosystem":"npm","package":"@prompty/core","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.1.5"}]}]},{"source":"osv","ecosystem":"npm","package":"@prompty/core","ranges":[{"type":"SEMVER","events":[{"introduced":"2.0.0-alpha.1"},{"fixed":"2.0.0-beta.5"}]}]}],"products":[{"vendor":"microsoft","product":"prompty"}],"references":[{"url":"https://github.com/microsoft/prompty/security/advisories/GHSA-w28w-gp39-m4p6","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/microsoft/prompty/pull/404","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/microsoft/prompty/pull/405","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/microsoft/prompty/commit/e4a0ebf49e3a78d5d7796c8480bf9a4f0c54d19e","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/microsoft/prompty/commit/f5c57c94a0990cca79d095c3daab661b4b1fb89f","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/microsoft/prompty/tree/typescript/2.0.0-beta.5","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/microsoft/prompty/commit/047756f4c8caf91c5868eeb42520c938393277b0","tags":["web"]},{"url":"https://github.com/advisories/GHSA-w28w-gp39-m4p6"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73299.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73299","tags":["advisory"]},{"url":"https://github.com/microsoft/prompty","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-73299","title":"Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer","description":"Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 0.1.5 and 2.0.0-beta.5, the TypeScript Nunjucks renderer evaluated untrusted .prompty template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process. This issue is fixed in versions 0.1.5 and 2.0.0-beta.5.","status":"published","published":"2026-08-12T17:31:38.807Z","modified":"2026-08-12T18:54:20.646Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-94","CWE-1336"],"updated_at":"2026-11-02T13:43:33.766176Z"}],"euvd":[{"id":"EUVD-2026-57382","description":"Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 0.1.5 and 2.0.0-beta.5, the TypeScript Nunjucks renderer evaluated untrusted .prompty template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process. This issue is fixed in versions 0.1.5 and 2.0.0-beta.5.","status":"published","published":"2026-08-12T17:31:38Z","modified":"2026-08-12T18:54:20Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T18:01:57.953172Z"}],"ghsa":[{"id":"GHSA-w28w-gp39-m4p6","title":"Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer","description":"## Summary\nThe TypeScript Nunjucks renderer evaluated untrusted `.prompty` template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process.\n\n## Affected packages\n- npm `@prompty/core` versions `\u003c= 0.1.4`\n- npm `@prompty/core` versions `\u003c= 2.0.0-beta.4`\n\n## Impact\nApplications that render untrusted, community-supplied, cloned, or LLM-generated `.prompty` files with the TypeScript runtime could allow attacker-controlled code execution with the privileges of the Node.js host process.\n\n## Remediation\nUpgrade to `@prompty/core` `2.0.0-beta.5` or later. The patched renderer sanitizes render inputs to own-data-only values, rejects constructor/prototype member traversal, and disallows template function calls. Ordinary interpolation, conditionals, loops, and own nested data properties remain supported.\n\n## Fix details\nThe fix is merged in PR #404 and includes regression coverage for default Nunjucks rendering, explicit renderer usage, unsafe member lookups, and attempted template function calls.","status":"published","published":"2026-07-24T16:23:59Z","modified":"2026-07-24T16:24:00Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-94","CWE-1336"],"updated_at":"2026-11-02T14:40:52.46233Z"}],"nvd":[{"id":"CVE-2026-73299","description":"Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 0.1.5 and 2.0.0-beta.5, the TypeScript Nunjucks renderer evaluated untrusted .prompty template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process. This issue is fixed in versions 0.1.5 and 2.0.0-beta.5.","status":"published","published":"2026-08-12T18:18:15.197Z","modified":"2026-10-24T15:10:00.19Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-94","CWE-1336"],"updated_at":"2026-11-02T14:12:37.217486Z"}],"osv":[{"id":"CVE-2026-73299","title":"Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer","description":"Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 0.1.5 and 2.0.0-beta.5, the TypeScript Nunjucks renderer evaluated untrusted .prompty template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process. This issue is fixed in versions 0.1.5 and 2.0.0-beta.5.","status":"published","published":"2026-08-12T17:31:38.807Z","modified":"2026-10-28T02:30:49.120014686Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-1336","CWE-94"],"updated_at":"2026-11-02T15:45:16.365946Z"},{"id":"GHSA-w28w-gp39-m4p6","title":"Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer","description":"## Summary\nThe TypeScript Nunjucks renderer evaluated untrusted `.prompty` template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process.\n\n## Affected packages\n- npm `@prompty/core` versions `\u003c= 0.1.4`\n- npm `@prompty/core` versions `\u003c= 2.0.0-beta.4`\n\n## Impact\nApplications that render untrusted, community-supplied, cloned, or LLM-generated `.prompty` files with the TypeScript runtime could allow attacker-controlled code execution with the privileges of the Node.js host process.\n\n## Remediation\nUpgrade to `@prompty/core` `2.0.0-beta.5` or later. The patched renderer sanitizes render inputs to own-data-only values, rejects constructor/prototype member traversal, and disallows template function calls. Ordinary interpolation, conditionals, loops, and own nested data properties remain supported.\n\n## Fix details\nThe fix is merged in PR #404 and includes regression coverage for default Nunjucks rendering, explicit renderer usage, unsafe member lookups, and attempted template function calls.","status":"published","published":"2026-07-24T16:23:59Z","modified":"2026-08-13T04:11:08.015471511Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-1336","CWE-94"],"updated_at":"2026-11-02T15:46:58.04805Z"}]}}