CVE-2026-2391: ### Summary The `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true

Q: How do I fix CVE-2026-2391?

qs: upgrade to 6.14.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-2391 being exploited?

CVE-2026-2391 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-2391 affect?

CVE-2026-2391 affects qs. Severity is low (CVSS 3.7). ### Summary The `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement

Q: How urgent is CVE-2026-2391?

Priority 34/100. Public exploit reference; Remotely exploitable, no login, no user action

This week

LOW 3.7REMOTEUPGRADE

CVE-2026-2391 is a low-severity flaw (CVSS 3.7) affecting qs. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

### Summary The `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284). ### Details When the `comma` option is set to `true` (not the default, but configurable in applications), qs allows p

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	3.7 (Low)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 55%)
CISA exploited list	No
Weakness	CWE-20
Published	2026-02-12
Last modified	2026-06-17

Publisher (CNA): harborist · Vendor: qs project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-02-12 05:17 UTCPublished CVE record published
2026-06-17 10:30 UTCUpdated Record last modified

qs project qs UPGRADE

Affected: >= 6.7.0 and < 6.14.2

Fixed in: 6.14.2

Safe to downgrade to: a release before 6.7.0

1. Check installed version

npm ls qs

2. UPGRADE to 6.14.2

npm install qs@">=6.14.2"

3. If no update is available yet, DOWNGRADE to a release before 6.7.0

npm view qs versions npm install qs@"<6.7.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Advisories and coverage

Official advisories

Express Releases: v5.3.0 2026-10-09

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-2391?

qs: upgrade to 6.14.2. Exact commands for each OS are on this page.

Is CVE-2026-2391 being exploited?

CVE-2026-2391 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-2391 affect?

CVE-2026-2391 affects qs. Severity is low (CVSS 3.7). ### Summary The `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement

How urgent is CVE-2026-2391?

Priority 34/100. Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2025-15284 LOW 3.7 UPGRADE Improper Input Validation vulnerability in qs (parse modules) allows HTTP DoS.This issue affects qs: < 6.14.1.

References

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