Vulnerability in qs (CVE-2026-8723)
Summary
Vulnerability in qs (CVE-2026-8723). Risk of unauthorized operations or information disclosure. Exploitable via qs.stringify. Mitigation: upgrade to 0c180a4 or later.
Original description
The description as published by the source.
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:
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
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/string…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-8723 has been found in qs.
Attackers can target a specific entry point like qs.stringify over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade qs to 0c180a4 or later.
If unsure, ask your IT team or search "qs CVE-2026-8723" on the vendor's site.
CVE-2026-8723 (qs) — CWE-476 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: qs.stringify / TypeError / null / undefined
Patched: 0c180a4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-476) exists in qs. Attackers reach the vulnerable code path via qs.stringify without authentication.
Check the vendor advisory for the affected versions of qs. Attack surface: qs.stringify / TypeError / null / undefined.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 0c180a4.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'qs' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'qs' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
qsを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade qs to 0c180a4ステージング環境で 0c180a4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-8723 node-qs
- Ubuntu UBUNTU-CVE-2026-8723 node-qs
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- patch github.com
- web github.com
- web npmjs.com