mailparser vulnerable to Cross-site Scripting

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.0 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:P · score source

EPSS

• CVE-2026-3455: 0.36% estimated exploitation activity in the next 30 days; percentile 30.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Versions of the package mailparser before 3.9.3 are vulnerable to Cross-site Scripting (XSS) via the textToHtml() function due to the improper sanitisation of URLs in the email content. An attacker can execute arbitrary scripts in victim browsers by adding extra quote " to the URL with embedded malicious JavaScript code.

Published by the source

3 Mar 2026, 06:31 UTC

Last modified by the source

4 Mar 2026, 20:41 UTC

Source last checked

26 Oct 2026, 12:42 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-7gmj-h9xc-mcxc

2. Revision 2 · amended · 24 Oct 2026

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

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-7gmj-h9xc-mcxc

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# Patch Next advisory brief: CVE-2026-3455

Advisory: mailparser vulnerable to Cross-site Scripting
IDs: CVE-2026-3455, GHSA-7gmj-h9xc-mcxc
Record: https://patchnext.com/advisories/cve-2026-3455 (revision 3, source checked 26 Oct 2026, 12:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mailparser 3.9.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm mailparser: affected < 3.9.3; fixed in 3.9.3

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mailparser.
- 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-7gmj-h9xc-mcxc (OSV record GHSA-7gmj-h9xc-mcxc lists affected ranges: npm mailparser >=0 <3.9.3 (fixed))
- Verified: https://github.com/advisories/GHSA-7gmj-h9xc-mcxc (GitHub-reviewed advisory GHSA-7gmj-h9xc-mcxc lists affected ranges: npm mailparser >=0 <3.9.3)

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