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Low, CVSS 2.1amended

Blitz has a Cross-site Scripting issue

CVE-2026-9520GHSA-h2p9-cr4h-px24

What to do

Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm blitz

    Affected
    <= 3.0.2
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
2.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P · score source
EPSS
  • CVE-2026-9520: 0.34% estimated exploitation activity in the next 30 days; percentile 27.04 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

A weakness has been identified in blitz-js blitz up to 3.0.2 on GitHub. This impacts an unknown function of the file packages/generator/templates/app/src/app/auth/components/LoginForm.tsx of the component Sign-in. This manipulation of the argument Next causes cross site scripting. It is possible to initiate the attack remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-h2p9-cr4h-px24

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-h2p9-cr4h-px24

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-9520

Advisory: Blitz has a Cross-site Scripting issue
IDs: CVE-2026-9520, GHSA-h2p9-cr4h-px24
Record: https://patchnext.com/advisories/cve-2026-9520 (revision 3, source checked 26 Oct 2026, 12:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm blitz: affected <= 3.0.2

## Suggested inspection (read-only)
- `npm ls blitz --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on blitz.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-h2p9-cr4h-px24 (OSV record GHSA-h2p9-cr4h-px24 lists affected ranges: npm blitz >=0 <=3.0.2)
- Verified: https://github.com/advisories/GHSA-h2p9-cr4h-px24 (GitHub-reviewed advisory GHSA-h2p9-cr4h-px24 lists affected ranges: npm blitz >=0 <=3.0.2)

Commands are suggestions: review each one before running it.

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