CISA orders agencies to patch MongoDB MongoBleed flaw

Introduction

On December 29, 2025, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2025-14847 - commonly referred to as "MongoBleed" - to its Known Exploited Vulnerabilities (KEV) catalog and directed Federal Civilian Executive Branch (FCEB) agencies to remediate within three weeks, setting a due date of January 19, 2026.

MongoDB says the issue affects MongoDB Server (Community and Enterprise), and emphasized that it is not a breach of MongoDB's own systems or MongoDB Atlas. Atlas fleets were patched by MongoDB as part of its managed service operations, while self-managed deployments must be updated by operators.

What happened

CISA's KEV entry reflects evidence that CVE-2025-14847 is being exploited in real-world attacks and requires agencies to "apply mitigations per vendor instructions," follow applicable cloud guidance, or discontinue use if mitigations are unavailable.

Key points confirmed across vendor and government advisories:

• KEV added: December 29, 2025
• FCEB remediation deadline: January 19, 2026
• Attack type: pre-authentication information disclosure (memory leak) via malformed zlib-compressed protocol messages
• Immediate workaround (if you can't patch): disable zlib compression

Technical details

CVE-2025-14847 is a server-side memory disclosure flaw caused by mismatched length fields in zlib-compressed MongoDB protocol headers. Because the vulnerable logic is reached before authentication, an unauthenticated client can trigger MongoDB Server to return uninitialized heap memory. In practical terms, that leaked memory can contain fragments of sensitive data present in-process (for example, credentials, tokens, or other secrets handled by applications).

Wiz's technical summary describes the issue in MongoDB's zlib decompression path and notes that internet-exposed MongoDB servers are especially at risk because the flaw is reachable without credentials.

Who is affected and why it matters

This issue impacts multiple supported and legacy MongoDB Server versions, including older release lines where organizations may still run self-hosted databases.

Risk is highest when:

• MongoDB is reachable over the network, especially if exposed to the public internet.
• The instance is running an affected version.
• zlib compression is enabled (commonly enabled by default in many deployments, per multiple advisories).

Operational consequences are primarily confidentiality-related (information disclosure), but the business impact can still be severe: leaked secrets can enable follow-on access, lateral movement, or compromise of adjacent services that reuse exposed credentials or tokens.

Active exploitation and threat landscape

CISA's inclusion of CVE-2025-14847 in the KEV catalog indicates exploitation has been observed and is considered operationally relevant for federal agencies.

Wiz reported exploitation activity and noted that a working exploit became publicly available on December 26, 2025, increasing the likelihood of rapid opportunistic scanning against exposed MongoDB services.

Separately, exposure telemetry cited by Wiz suggested broad cloud prevalence: 42% of cloud environments in its dataset had at least one vulnerable MongoDB instance (including internal and public-facing resources).

Recommended mitigations and workarounds

Patch (preferred and required for full remediation)

Upgrade to fixed versions as published by authoritative advisories. The Canadian Centre for Cyber Security provides a clear fixed-version matrix across supported branches, including:

• MongoDB 8.2.3 (fixes 8.2.0-8.2.2)
• MongoDB 8.0.17 (fixes 8.0.0-8.0.16)
• MongoDB 7.0.28 (fixes 7.0.0-7.0.27)
• MongoDB 6.0.27 (fixes 6.0.0-6.0.26)
• MongoDB 5.0.32 (fixes 5.0.0-5.0.31)
• MongoDB 4.4.30 (fixes 4.4.0-4.4.29)

For older legacy lines (e.g., 4.2/4.0/3.6), the Canadian advisory indicates no vendor fix and recommends upgrading to a fixed version on a supported branch.

Temporary mitigation (when patching must be delayed)

If you cannot patch immediately, disable zlib compression at the server level by configuring MongoDB to omit zlib (for example, using other compressors or disabling compression).

Reduce exposure

• Restrict network access to MongoDB to trusted sources (security groups, firewalls, private networking).
• Avoid direct internet exposure of port 27017/TCP.
• Confirm authentication is enabled and appropriately enforced.

Shadowserver notes it tracks internet-exposed MongoDB and added tagging for CVE-2025-14847 in its exposure reporting, reinforcing the operational focus on reducing external attack surface.

Detection and triage

• Review MongoDB logs for anomalous pre-authentication behavior and unexpected errors.
• Use available log-parsing detection utilities where appropriate; BleepingComputer highlights a "MongoBleed Detector" intended to help identify potential exploitation attempts in MongoDB logs.

Vendor and government response

• MongoDB published a security update and outlined its internal discovery and response timeline, emphasizing that Atlas was patched as part of managed operations and that customers should run fixed versions.
• CISA set the FCEB remediation deadline at January 19, 2026 via KEV-driven operational requirements.
• Canadian Centre for Cyber Security issued an alert with affected/fixed versions and mitigation guidance, including disabling zlib compression when patching is not immediately possible.

Organizations outside the U.S. federal scope can still use KEV status as a strong prioritization signal: it indicates active exploitation and tends to correlate with widespread scanning for exposed services.

Conclusion

If you run self-managed MongoDB, prioritize identifying vulnerable versions and upgrading to fixed releases immediately. Where patching is delayed, disable zlib compression and reduce network exposure - especially any internet-facing MongoDB services - while monitoring logs for suspicious pre-auth behavior and indicators of attempted exploitation.