express-xss-sanitizer has an unbounded recursion depth

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2025-59364: 0.45% estimated exploitation activity in the next 30 days; percentile 39.08 (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.

Security Advisory: express-xss-sanitizer Overview A vulnerability was discovered in express-xss-sanitizer that allowed unbounded recursion depth during sanitization of nested objects. Affected Versions - All versions prior to 2.0.1 Patched Versions - 2.0.1 and later Description The sanitize function in lib/sanitize.js performed recursive sanitization without depth limiting, making it vulnerable to stack overflow attacks via specially crafted deeply nested JSON objects. Impact An attacker could cause denial-of-service by sending a request with deeply nested structures, potentially crashing the Node.js process. Solution Upgrade to version 2.0.1 or later:

Published by the source

26 Sep 2025, 14:38 UTC

Last modified by the source

26 Sep 2025, 14:57 UTC

Source last checked

26 Oct 2026, 12:38 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-hvq2-wf92-j4f3

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-hvq2-wf92-j4f3

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# Patch Next advisory brief: CVE-2025-59364

Advisory: express-xss-sanitizer has an unbounded recursion depth
IDs: CVE-2025-59364, GHSA-hvq2-wf92-j4f3
Record: https://patchnext.com/advisories/cve-2025-59364 (revision 3, source checked 26 Oct 2026, 12:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: express-xss-sanitizer 2.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm express-xss-sanitizer: affected < 2.0.1; fixed in 2.0.1

## Suggested inspection (read-only)
- `npm ls express-xss-sanitizer --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 express-xss-sanitizer.
- 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-hvq2-wf92-j4f3 (OSV record GHSA-hvq2-wf92-j4f3 lists affected ranges: npm express-xss-sanitizer >=0 <2.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-hvq2-wf92-j4f3 (GitHub-reviewed advisory GHSA-hvq2-wf92-j4f3 lists affected ranges: npm express-xss-sanitizer >=0 <2.0.1)

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