# CVE-2026-120819: Use-after-free in Wasm JS-BSON bridge lets read-only users read 24 KiB via $accumulator

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

A memory-management flaw in the server-side JavaScript execution component of MongoDB Server can allow an authenticated user holding only read privileges to cause the server to access memory that has already been released. By submitting a specially crafted database command that runs user-supplied JavaScript, the user can cause a bounded amount of adjacent process memory to be returned in the command's result. This results in the user obtaining information they are not authorized to access. Integrity and availability are not affected.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- MongoDB / MongoDB Server: ≥ 9.0.0; < 9.0.7 (affected, semver). Source: CNA: mongodb

## Severity and prioritization

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/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: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/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: 0.38% as of 2026-11-13; percentile 32.62%

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

- Weaknesses: CWE-416

## Exploit evidence

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

## References

- https://jira.mongodb.org/browse/SERVER-134893 (CNA: mongodb)

- https://jira.mongodb.org/browse/SERVER-134893 (cna@mongodb.com)

## Provenance

- CNA: mongodb: https://www.cve.org/CVERecord?id=CVE-2026-120819; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-120819; retrieved 2026-11-11; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-120819; retrieved 2026-11-13; source updated Not reported

Revision: b68fdfc8df50aecbb2bed61914032679d91f1a9c77a71dae8a4aaa2293dd872d

Canonical: https://y2.dev/cve/CVE-2026-120819

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

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