AEGLIX vulnerability intelligence
CVE-2026-110816
MEDIUM · CVSS 6.3 · Awaiting Analysis
Published: 2026-10-14 · Updated: 2026-10-16 · Source: NVD
Stored catalog record
Source record retrieved 2026-10-28T10:22:31.261633+00:00. Scheduled imports handle updates; this page does not assert that the provider was queried just now.
Vulnerability overview
### Summary `qs.stringify` with `arrayFormat: 'comma'` throws `TypeError: Cannot convert object to primitive value` when an array element cannot be coerced to a string, such as an object with an own non-callable `toString` (`{ "toString": "x" }`) or a null-prototype object. The comma format joins array elements with `Array.prototype.join` and, under `encodeValuesOnly`, first passes each element through `String()` in `utils.encode`; neither guards against an element whose string coercion fails. ### Details In `lib/stringify.js`, the comma branch collapses the array with `obj.join(',')`. For an element whose own `toString` is not callable, `ToPrimitive` skips it, falls through to `Object.prototype.valueOf` (which returns the object itself), and throws. Under `encodeValuesOnly: true`, the same element first reaches `String(str)` in `utils.encode` (`lib/utils.js`) and throws there. Nested arrays (`{ "a": [[{ "toString": "x" }]] }`) throw the same way, through `Array.prototype.toString`. The `indices`, `brackets`, and `repeat` formats walk into object elements instead of coercing them, and are not affected. Such elements can come from untrusted input. `JSON.parse` produces `{ "a": [{ "toString": "x" }] }` with no qs option involved. `qs.parse("a[0][toString]=x", { allowPrototypes: true })` keeps the `toString` key, and `qs.parse("a[][b]=c", { plainObjects: true })` produces a null-prototype element; the default parse options drop `toString` and produce ordinary objects, which do not throw. Express 4's default `query parser`, Express 5's `extended` query parser, and body-parser's `urlencoded({ extended: true })` all call `qs.parse` with `allowPrototypes: true`. #### PoC ```js var qs = require("qs"); qs.stringify(JSON.parse("{\"a\":[{\"toString\":\"x\"}]}"), { arrayFormat: "comma" }); qs.stringify(qs.parse("a[0][toString]=x", { allowPrototypes: true }), { arrayFormat: "comma" }); qs.stringify(qs.parse("a[][b]=c", { plainObjects: true }), { arrayFormat: "comma", encodeValuesOnly: true }); // TypeError: Cannot convert object to primitive value ``` #### Fix Applied in a952e75 on `main` and released as v6.16.1: an element whose string coercion would fail is coerced to its primitive `valueOf`, if any, or else to `Object.prototype.toString`, so it renders as `[object Object]`, the same as any other object element already does under the comma format. Nested arrays are walked the way `join` walks them. Every input that did not previously throw serializes exactly as before, and a `toString` or `valueOf` that itself throws still propagates. ### Affected versions `>=6.7.0 <6.16.1`, fixed in v6.16.1. The `join` path was introduced with the comma format in b84acba and first shipped in v6.7.0; v6.6.x and earlier ignore `arrayFormat: 'comma'` and are not affected. The `encodeValuesOnly` `String()` site was introduced in 4c4b23d (v6.11.1); before that, the same input throws at `join`. Every release from v6.7.0 through v6.16.0 is affected. ### Impact An unauthenticated request can make any code path that re-serializes attacker-influenced data with `qs.stringify` and `arrayFormat: 'comma'` (for example, rebuilding a query string from `req.query` for a redirect or an upstream request, or serializing a parsed JSON body) throw synchronously. In a typical Node.js HTTP framework the throw is caught by the framework error boundary and the affected request returns a 500; the process survives and other requests are unaffected. Where the call runs outside an error boundary, such as an `async` Express 4 handler (where the throw becomes an unhandled promise rejection) or a bare `http` request handler, the process exits, so the impact in that case depends on the application error handling rather than on qs. The default `arrayFormat` (`indices`) is not affected.
Patch review priority
Assess exposure and vendor guidance
- No higher-priority signal is available in the current stored evidence.
FIRST EPSS: 0.37% · percentile 30.5 · score date 2026-10-27.
EPSS estimates probability of exploitation in the next 30 days. It does not measure your exposure or prove exploitation. The elevated threshold is 10%; CISA KEV takes precedence. About FIRST EPSS ↗
Severity and scoring
- CVSS score
- 6.3 · MEDIUM
- CVSS version
- 4.0
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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
- Weaknesses
- CWE-248, CWE-704
CVSS measures technical severity; it does not establish whether this vulnerability is being exploited in your environment.
Known exploitation and remediation
Not listed in the CISA catalog retrieved for this record. This does not establish that exploitation has not occurred.
Verify affected versions and patch availability in the vendor advisory before making changes.
Affected products and versions
NVD has not supplied affected-version configurations for this record. Check the vendor references below.