CVE-2026-82562

Description

### Summary When `qs.parse` is called with `comma: true` and `throwOnLimitExceeded: true`, a comma-separated value under a bracket-push key (`a[]=1,2,3,4`) is split into an array without being compared against `arrayLimit`, while the same value under a flat key (`a=1,2,3,4`), an indexed key (`a[0]=`), a nested key (`a[b]=`), or a dotted key (`a.b=` with `allowDots`) throws the documented `RangeError`. A single parameter such as `a[]=1,2,2,...` therefore produces an inner array of arbitrary length even though the caller opted into the hard limit. This is the `[]=` key form that the fix for CVE-2026-2391 (qs 6.14.2) did not cover. ### Details In `lib/parse.js`, a comma-separated value under a `[]=` key is split and then wrapped as a single nested element (`val = [val]`, so that each `a[]=x,y` group counts as one element of the outer array). The `arrayLimit` check that 6.14.2 added for comma values runs after that wrap, so for `[]=` parts it only ever saw the wrapper of length 1. 6.15.3 added a pre-split comma count so that an oversized value throws before it is allocated, but gated it on an `isFlatArrayValue` flag that `parseValues` set to `false` for any part containing `[]=`, and did not pass it for object-valued input, so the gap remained. #### PoC ```js var qs = require('qs'); var options = { comma: true, arrayLimit: 3, throwOnLimitExceeded: true }; qs.parse('a=1,2,3,4', options); // RangeError: Array limit exceeded. Only 3 elements allowed in an array. qs.parse('a[]=1,2,3,4', options); // { a: [ [ '1', '2', '3', '4' ] ] } (no throw) qs.parse('a[]=' + '1,'.repeat(1000000) + '1', { comma: true, arrayLimit: 20, throwOnLimitExceeded: true }); // no throw; a 1,000,001-element inner array is allocated ``` #### Fix `lib/parse.js`, applied in 8859c37 on `main` and released as v6.16.0: the `isFlatArrayValue` gate is removed, so every comma-split value is counted against `arrayLimit` before splitting regardless of key form. An in-limit group under `a[]=` still counts as one element of the outer array, and the default (`throwOnLimitExceeded: false`) path is unchanged. ### Affected versions `>=6.14.2 <6.16.0`, fixed in v6.16.0. v6.14.2 introduced `arrayLimit` enforcement for comma values (the fix for CVE-2026-2391) but only for values not under a `[]=` key, and every release from v6.14.2 through v6.15.3 has the same gap. v6.14.0 and v6.14.1, where `throwOnLimitExceeded` exists but does not apply to any comma form, are covered by CVE-2026-2391 rather than this record. Earlier lines (6.7.x through 6.13.x) have `comma` but no `throwOnLimitExceeded`, so there is no hard cap on any comma path to bypass; releases before 6.7.0 have no `comma` option. ### Impact An unauthenticated attacker who can reach an application that parses untrusted query strings or urlencoded bodies with both `comma: true` and `throwOnLimitExceeded: true` (both non-default) can bypass the configured limit with a single `a[]=` parameter and force the parser to allocate an array proportional to the request size. The cost is strictly linear in the attacker-supplied bytes (about 0.1 microseconds and 6 to 7 retained bytes per input byte; the same out-of-memory threshold as the documented default `throwOnLimitExceeded: false` path), so a transport-layer request or body size limit bounds it completely (and node's default maximum HTTP header size of 16 KB already bounds the request line, so multi-megabyte payloads need a body parser). The impact is that an opt-in hard limit fails open on one key spelling, not unbounded allocation from a small input.

CVSS Metrics

• v4.0•MEDIUM•Score: 6.3CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
• v4.0•MEDIUM•Score: 6.3CVSS: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
• v3.1•LOW•Score: 3.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Trends

Current EPSS score: 0.32%• Percentile: 25%

Techniques & Countermeasures

• CWE-770•Allocation of Resources Without Limits or Throttling

  The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Affected Systems

• chainguard•arangodb-3.12

  < 3.12.9.4-r31

• chainguard•argo-workflows-ui-4.0

  < 4.0.11-r0

• chainguard•azurite

  < 3.36.0-r4

• chainguard•code-server

  < 4.135.0-r2

• chainguard•commercial-gitlab-rails-ee-19.1

  all

• chainguard•commercial-gitlab-rails-ee-19.2

  all

• chainguard•commercial-gitlab-rails-ee-19.3

  all

• chainguard•commercial-gitlab-rails-ee-fips-19.1

  all

• chainguard•commercial-gitlab-rails-ee-fips-19.3

  all

• chainguard•dotstatsuite-supercore

  < 3.1.0_git20260903-r0

• chainguard•gitlab-rails-ce-18.11

  all

• chainguard•gitlab-rails-ce-19.1

  all | < 19.1.7-r6

• chainguard•gitlab-rails-ce-19.3

  < 19.3.1-r6

• chainguard•gitlab-rails-ce-fips-18.11

  all

• chainguard•json-server

  all | < 0.17.4-r13

• chainguard•kibana-9.2

  all

• chainguard•kibana-9.2-iamguarded

  all

• chainguard•kibana-9.3

  all

• chainguard•kibana-9.3-iamguarded

  all

• chainguard•kibana-9.4

  < 9.4.6-r2

• chainguard•kibana-9.4-iamguarded

  < 9.4.6-r2

• chainguard•kibana-9.5

  < 9.5.3-r1

• chainguard•kibana-9.5-iamguarded

  < 9.5.3-r1

• chainguard•kubeflow-centraldashboard

  < 2.0.0-r2

• chainguard•kubescape-grype-offline-db

  all | < 0_git20250804-r6

• chainguard•langfuse-3

  all | < 3.225.7-r1

• chainguard•langfuse-3-compat

  < 3.225.7-r6

• chainguard•langfuse-3-worker

  all | < 3.225.7-r1

• chainguard•langfuse-4

  < 4.27.0-r3

• chainguard•langfuse-4-worker

  < 4.27.0-r3

• chainguard•langfuse-fips-3

  < 3.225.5-r2

• chainguard•langfuse-fips-3-worker

  < 3.225.5-r2

• chainguard•langfuse-fips-4

  < 4.26.0-r1

• chainguard•langfuse-fips-4-worker

  < 4.26.0-r1

• chainguard•opensearch-dashboards-2

  < 2.19.6-r16

• chainguard•opensearch-dashboards-2-alerting-dashboards-plugin

  < 2.19.6-r17

• chainguard•opensearch-dashboards-2-anomaly-detection-dashboards-plugin

  < 2.19.6-r16

• chainguard•opensearch-dashboards-2-dashboards-maps

  < 2.19.6-r16

• chainguard•opensearch-dashboards-2-dashboards-notifications

  < 2.19.6-r16

• chainguard•opensearch-dashboards-2-dashboards-observability

  < 2.19.6-r16

• chainguard•opensearch-dashboards-2-dashboards-query-workbench

  < 2.19.6-r16

• chainguard•opensearch-dashboards-2-dashboards-reporting

  < 2.19.6-r17

• chainguard•opensearch-dashboards-2-dashboards-search-relevance

  < 2.19.6-r16

• chainguard•opensearch-dashboards-2-dashboards-visualizations

  < 2.19.6-r16

• chainguard•opensearch-dashboards-2-fips

  < 2.19.6-r5

• chainguard•opensearch-dashboards-2-fips-alerting-dashboards-plugin

  < 2.19.6-r6

• chainguard•opensearch-dashboards-2-fips-anomaly-detection-dashboards-plugin

  < 2.19.6-r5

• chainguard•opensearch-dashboards-2-fips-dashboards-maps

  < 2.19.6-r5

• chainguard•opensearch-dashboards-2-fips-dashboards-notifications

  < 2.19.6-r5

• chainguard•opensearch-dashboards-2-fips-dashboards-observability

  < 2.19.6-r5

Showing first 50 affected entries in server-rendered view.

References (10)

• https://github.com/ljharb/qs/security/advisories/GHSA-x5fp-wj9c-mxmx
• https://github.com/ljharb/qs/commit/8859c37470e11b42b547b275e4e9bd0bc8cc5464
• https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883
• https://security-tracker.debian.org/tracker/CVE-2026-82562
• https://ubuntu.com/security/CVE-2026-82562
• https://www.cve.org/CVERecord?id=CVE-2026-82562
• https://nvd.nist.gov/vuln/detail/CVE-2026-82562
• https://github.com/ljharb/qs
• https://npmjs.com/qs
• https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82562.json