### Summary `qs.stringify` throws `TypeError` when called with `arrayFormat: 'comma'` and `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not handled by any of qs's null-related options (`skipNulls`, `strictNullHandling`). ### Details In the comma + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before joining: ```js obj = utils.maybeMap(obj, encoder); ``` `utils.encode` (`lib/utils.js:195`) reads `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to run. Same class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + `encodeValuesOnly` branch was introduced in 4c4b23d ("encode comma values more consistently", PR #463, 2023-01-19), first released in v6.11.1. #### PoC ```js const qs = require('qs'); qs.stringify({ a: [null, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true }); qs.stringify({ a: [undefined, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true }); qs.stringify({ a: [null] }, { arrayFormat: 'comma', encodeValuesOnly: true }); // TypeError: Cannot read properties of null (reading 'length') // at encode (lib/utils.js:195:13) // at Object.maybeMap (lib/utils.js:322:37) // at stringify (lib/stringify.js:145:25) ``` #### Fix `lib/stringify.js:145`, applied in 21f80b3 on `main` and released as v6.15.2: ```diff - obj = utils.maybeMap(obj, encoder); + obj = utils.maybeMap(obj, function (v) { + return v == null ? v : encoder(v); + }); ``` `null` and `undefined` now pass through `maybeMap` unchanged and reach the `join(',')` step as-is. For `{ a: [null, 'b'] }` this produces `a=,b`, matching the non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same input). Single-element `[null]` arrays still collapse via the existing `obj.join(',') || null` and remain subject to `skipNulls` / `strictNullHandling` in the main loop. ### Affected versions `>=6.11.1 <6.15.2` — fixed in v6.15.2. The vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions — including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 — implemented the comma + `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified across released versions. ### Impact Application code that calls `qs.stringify` with both `arrayFormat: 'comma'` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined` array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework's error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The "kills the worker process" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled. The vulnerable input is a `null` or `undefined` entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - ### Summary `qs.stringify` throws `TypeError` when called with `arrayFormat: 'comma'` and
    `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not
    handled by any of qs's null-related options (`skipNulls`, `strictNullHandling`). ### Details In the comma
    + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before
    joining: ```js obj = utils.maybeMap(obj, encoder); ``` `utils.encode` (`lib/utils.js:195`) reads
    `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and
    `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to
    run. Same class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma +
    `encodeValuesOnly` branch was introduced in 4c4b23d ("encode comma values more consistently", PR #463,
    2023-01-19), first released in v6.11.1. #### PoC ```js const qs = require('qs'); qs.stringify({ a: [null,
    'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true }); qs.stringify({ a: [undefined, 'b'] }, {
    arrayFormat: 'comma', encodeValuesOnly: true }); qs.stringify({ a: [null] }, { arrayFormat: 'comma',
    encodeValuesOnly: true }); // TypeError: Cannot read properties of null (reading 'length') // at encode
    (lib/utils.js:195:13) // at Object.maybeMap (lib/utils.js:322:37) // at stringify
    (lib/stringify.js:145:25) ``` #### Fix `lib/stringify.js:145`, applied in 21f80b3 on `main` and released
    as v6.15.2: ```diff - obj = utils.maybeMap(obj, encoder); + obj = utils.maybeMap(obj, function (v) { +
    return v == null ? v : encoder(v); + }); ``` `null` and `undefined` now pass through `maybeMap` unchanged
    and reach the `join(',')` step as-is. For `{ a: [null, 'b'] }` this produces `a=,b`, matching the
    non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same
    input). Single-element `[null]` arrays still collapse via the existing `obj.join(',') || null` and remain
    subject to `skipNulls` / `strictNullHandling` in the main loop. ### Affected versions `>=6.11.1 <6.15.2` —
    fixed in v6.15.2. The vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1.
    Earlier versions — including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 — implemented the comma +
    `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified
    across released versions. ### Impact Application code that calls `qs.stringify` with both `arrayFormat:
    'comma'` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined`
    array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP
    framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework's error boundary and the
    affected request returns a 500; the worker process does not exit and subsequent requests are unaffected.
    The "kills the worker process" framing applies only to call sites outside a request-handler error boundary
    (background jobs, startup paths, stream pipelines) or to deployments with framework error handling
    explicitly disabled. The vulnerable input is a `null` or `undefined` entry inside an array; this is
    reachable from JSON request bodies or from application code constructing arrays from user input, but not
    from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).
    (CVE-2026-8723)

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-ee50c21f92 advisory.

    33.0.6 Release

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-5afe6630dc advisory.

    33.0.6 Release

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - ### Summary `qs.stringify` throws `TypeError` when called with `arrayFormat: 'comma'` and     `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not     handled by any of qs's null-related options (`skipNulls`, `strictNullHandling`). ### Details In the comma     + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before     joining: ```js obj = utils.maybeMap(obj, encoder); ``` `utils.encode` (`lib/utils.js:195`) reads     `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and     `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to     run. Same class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma +     `encodeValuesOnly` branch was introduced in 4c4b23d (encode comma values more consistently, PR #463,     2023-01-19), first released in v6.11.1. #### PoC ```js const qs = require('qs'); qs.stringify({ a: [null,     'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true }); qs.stringify({ a: [undefined, 'b'] }, {     arrayFormat: 'comma', encodeValuesOnly: true }); qs.stringify({ a: [null] }, { arrayFormat: 'comma',     encodeValuesOnly: true }); // TypeError: Cannot read properties of null (reading 'length') // at encode     (lib/utils.js:195:13) // at Object.maybeMap (lib/utils.js:322:37) // at stringify     (lib/stringify.js:145:25) ``` #### Fix `lib/stringify.js:145`, applied in 21f80b3 on `main` and released     as v6.15.2: ```diff - obj = utils.maybeMap(obj, encoder); + obj = utils.maybeMap(obj, function (v) { +     return v == null ? v : encoder(v); + }); ``` `null` and `undefined` now pass through `maybeMap` unchanged     and reach the `join(',')` step as-is. For `{ a: [null, 'b'] }` this produces `a=,b`, matching the     non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same     input). Single-element `[null]` arrays still collapse via the existing `obj.join(',') || null` and remain     subject to `skipNulls` / `strictNullHandling` in the main loop. ### Affected versions `>=6.11.1 <6.15.2`     fixed in v6.15.2. The vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1.
    Earlier versions  including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0  implemented the comma +     `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified     across released versions. ### Impact Application code that calls `qs.stringify` with both `arrayFormat:
    'comma'` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined`     array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP     framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework's error boundary and the     affected request returns a 500; the worker process does not exit and subsequent requests are unaffected.
    The kills the worker process framing applies only to call sites outside a request-handler error boundary     (background jobs, startup paths, stream pipelines) or to deployments with framework error handling     explicitly disabled. The vulnerable input is a `null` or `undefined` entry inside an array; this is     reachable from JSON request bodies or from application code constructing arrays from user input, but not     from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).
    (CVE-2026-8723)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
462073	Echo: qs: security update to 6.15.2	Tenable Cloud Security	Echo Local Security Checks	Local	medium
462073	Echo: qs: security update to 6.15.2	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	medium
325136	Fedora 44 : nextcloud (2026-ee50c21f92)	Nessus	Fedora Local Security Checks	Local	high
325111	Fedora 43 : nextcloud (2026-5afe6630dc)	Nessus	Fedora Local Security Checks	Local	high
442333	SCA: security update for qs (GHSA-q8mj-m7cp-5q26)	Tenable Cloud Security	SCA Checks	Local	medium
442333	SCA: security update for qs (GHSA-q8mj-m7cp-5q26)	Tenable Self-Hosted Container Security	SCA Checks	Local	medium
315208	Linux Distros Unpatched Vulnerability : CVE-2026-8723	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2026-8723

medium

Tenable Plugins

medium

medium

high

high

medium

medium

medium