Security readout for executives and security teams
Plain-English summary
mongo-express could display stored database content without safe escaping. A person who can insert data into MongoDB may be able to make an administrator’s browser run script when the admin views affected rows or media-like cells, risking collection export or destructive admin actions.
Executive priority
Prioritize remediation for any exposed or shared mongo-express deployment because the issue targets administrators and can turn stored data into browser-executed actions with confidentiality and integrity impact.
Technical view
CVE-2021-21422 is stored XSS in mongo-express before v1.0.0-alpha.4. Large cell expansion could show unescaped full documents, and media-identified cells were rendered without sanitization. CVSS 3.1 is 8.1 high with network attack vector, no privileges required, and user interaction required.
Likely exposure
Exposure is likely where mongo-express versions earlier than v1.0.0-alpha.4 are deployed, especially if the admin UI is reachable by many users or displays data written by less-trusted users, services, imports, or integrations.
Exploitation context
The sources do not show CISA KEV listing or active exploitation. Exploitation requires malicious content to be present in a document and an administrator to interact with affected UI rendering. The advisory describes possible data export and database or collection deletion impacts.
Researcher notes
The evidence supports stored XSS through unescaped full-document display and unsanitized media rendering. Do not assume unauthenticated access to mongo-express itself; the described attacker needs a way to write data that an administrator later views.
Mitigation direction
- Upgrade mongo-express to v1.0.0-alpha.4 or later.
- Restrict mongo-express access to trusted administrators only.
- Limit network exposure of the mongo-express admin interface.
- Review write paths that place untrusted content into viewed collections.
- Follow the GitHub advisory if older versions cannot be upgraded immediately.
Validation and detection
- Inventory all mongo-express deployments and confirm their running versions.
- Check whether any deployment is older than v1.0.0-alpha.4.
- Review access controls for the mongo-express web interface.
- Identify collections populated by untrusted users, services, imports, or integrations.
- Confirm remediation by retesting version inventory and admin UI access restrictions.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupDatabase behavior lookup
The CVE wording references database injection or access, so collection and exfiltration review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-21422 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N2.85.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/mongo-express/mongo-express/security/advisories/GHSA-7p8h-86p5-wv3pCVE reference · x_refsource_CONFIRM
- https://github.com/mongo-express/mongo-express/issues/577CVE reference · x_refsource_MISC
- https://github.com/mongo-express/mongo-express/commit/f5e0d4931f856f032f22664b5e5901d5950cfd4bCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.