# CVE-2026-120816: System collection contents readable through a database change stream with showSystemEvents

Status: published. Published: 2026-11-10. Updated: 2026-11-13.

A user with basic read-tier database privileges can use an option on a server-side data-change notification feature to receive the contents of certain restricted internal collections that the same user is refused on a direct read. The privilege check for the notification feature is derived only from the target namespace and does not account for the option, so no additional permission is required. This may result in unintended access to data stored in those internal collections.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- MongoDB / MongoDB Server: ≥ 9.0.0; < 9.0.7 (affected, semver); ≥ 8.3.0; < 8.3.16 (affected, semver); ≥ 8.0.0; < 8.0.37 (affected, semver); ≥ 7.0.0; < 7.0.48 (affected, semver). Source: CNA: mongodb

## Severity and prioritization

- CVSS 4.0: 2.3 (low); CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N; source: CNA: mongodb

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N; source: CNA: mongodb

- CVSS 4.0: 2.3 (low); CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: cna@mongodb.com

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N; source: NVD: cna@mongodb.com

- CISA KEV: No listing in collected sources

- EPSS: 0.27% as of 2026-11-13; percentile 19.36%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-863

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://jira.mongodb.org/browse/SERVER-135203 (CNA: mongodb)

- https://jira.mongodb.org/browse/SERVER-135203 (cna@mongodb.com)

## Provenance

- CNA: mongodb: https://www.cve.org/CVERecord?id=CVE-2026-120816; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-120816; retrieved 2026-11-11; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-120816; retrieved 2026-11-13; source updated Not reported

Revision: 2ee6abd042edbea2d4eeb5f6b29c6b7bea56d589ea0f392d11c23ee5f351d638

Canonical: https://y2.dev/cve/CVE-2026-120816

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Collected public records only. Check source status for coverage and freshness.