CVE-2025-14847: MongoDB and MongoDB Server Improper Handling of Length Parameter Inconsistency Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run MongoDB MongoDB and MongoDB Server. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-12-29, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-01-19; treat that as the outer limit, not the target.
• EPSS 83.2%, percentile 99.7: FIRST’s model estimates a 83.2% chance of exploitation activity in the next 30 days, higher than 99.7% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Editorial verdict: Patch this week. MongoBleed: Pre-Auth Memory Leak in MongoDB Server — Atlas users are already patched; self-hosted MongoDB that untrusted networks can reach must be upgraded (or have zlib disabled) now, and internet-exposed instances should rotate credentials.

What it is

Mismatched length fields in Zlib compressed protocol headers may allow a read of uninitialized heap memory by an unauthenticated client. This issue affects all MongoDB Server v7.0 prior to 7.0.28 versions, MongoDB Server v8.0 versions prior to 8.0.17, MongoDB Server v8.2 versions prior to 8.2.3, MongoDB Server v6.0 versions prior to 6.0.27, MongoDB Server v5.0 versions prior to 5.0.32, MongoDB Server v4.4 versions prior to 4.4.30, MongoDB Server v4.2 versions greater than or equal to 4.2.0, MongoDB Server v4.0 versions greater than or equal to 4.0.0, and MongoDB Server v3.6 versions greater than or equal to 3.6.0.

CISA’s summary

MongoDB Server contains an improper handling of length parameter inconsistency vulnerability in Zlib compressed protocol headers. This vulnerability may allow a read of uninitialized heap memory by an unauthenticated client.

Weakness type: CWE-130.

Product: MongoDB MongoDB and MongoDB Server · Assigned by: mongodb · Published: 2025-12-19

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2025-12-29; federal due date 2026-01-19. Known ransomware use: Unknown.
• CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
• CISA SSVC assessment: exploitation active, automatable yes, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 83.22% probability of exploitation activity in the next 30 days; percentile 99.7.

Timeline

• 2025-12-19 — CVE record published by mongodb
• 2025-12-19 — erroneo.us brief: MongoBleed: Pre-Auth Memory Leak in MongoDB Server
• 2025-12-29 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-01-19 — CISA remediation deadline for US federal agencies
• 2026-02-26 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Listed in CISA KEV notes (jira.mongodb.org) jira.mongodb.org

Vulnerability records

1. CVE.org record CVE-2025-14847 cve.org
2. NVD entry CVE-2025-14847 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

Other references from the CVE record and advisory

1. openwall.com openwall.com
2. vicarius.io vicarius.io
3. vicarius.io vicarius.io
4. smartkeyss.com smartkeyss.com

All exploited MongoDB vulnerabilities · Today’s Security Digest