CVE-2025-14847: MongoDB Server zlib header length confusion leaks heap memory

Exploited in the wild High 8.7 EPSS 83.2% MongoDB Server

Mismatched length fields in zlib-compressed wire protocol headers let an unauthenticated client make MongoDB Server return uninitialized heap memory, which can contain data and secrets. Every server that accepts zlib compression over the network is exposed, across all versions back to 3.6. MongoDB fixed it in 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32 and 4.4.30 (no fix for 4.2, 4.0 or 3.6); CISA added it to KEV on 29 December 2025.

CVE-2025-14847CVE identifier
8.7CVSS 4.0 base score (high)
2025-12-29added to CISA's exploited list (US federal deadline 2026-01-19)
83.2%EPSS: chance of exploitation in the next 30 days (higher than 100% of CVEs)
2025-12-19published

What do these terms mean? CVE · CVSS score · exploited (KEV) · EPSS · backported fix · all terms

What to do now

Check whether you run MongoDB Server and which version (commands below).
Install the fixed version for your system: see “Patch it” below.
Restart mongod and mongos on every node (rolling restart for replica sets and sharded clusters).
If you cannot patch today, apply the temporary mitigation below and patch as soon as possible.
Because this flaw is being exploited, also check the server for signs of compromise.

Affected and fixed versions

Affected:

MongoDB 8.2 before 8.2.3
MongoDB 8.0 before 8.0.17
MongoDB 7.0 before 7.0.28
MongoDB 6.0 before 6.0.27
MongoDB 5.0 before 5.0.32
MongoDB 4.4 before 4.4.30
All MongoDB 4.2, 4.0 and 3.6 versions

Fixed in:

MongoDB 8.2.3
MongoDB 8.0.17
MongoDB 7.0.28
MongoDB 6.0.27
MongoDB 5.0.32
MongoDB 4.4.30

Am I affected?

mongod --version
grep -n -A2 compression /etc/mongod.conf

Patch it

Use the commands for your system. Distribution packages often keep an older version number with the fix backported, so compare with the fixed package versions in the table below, not only with the upstream version.

Debian

# MongoDB's own apt repository
sudo apt update
sudo apt install --only-upgrade mongodb-org
sudo systemctl restart mongod

Ubuntu

# MongoDB's own apt repository
sudo apt update
sudo apt install --only-upgrade mongodb-org
sudo systemctl restart mongod

RHEL, AlmaLinux, Rocky, Oracle

# MongoDB's own yum repository
sudo dnf upgrade 'mongodb-org*'
sudo systemctl restart mongod

Fedora

not packaged

SUSE / openSUSE

not in distro repos: repo.mongodb.org, mongodb-org-server

Amazon Linux

not in distro repos: repo.mongodb.org, mongodb-org-server

Arch Linux

not in official repos

Alpine

not packaged

FreeBSD

pkg update && pkg upgrade mongodb80 (mongodbNN)

General update steps for every system are on the Linux and Unix & BSD pages; after updating, see which services to restart.

Fix status in Linux distributions

Release	Package	Status	Fixed version / advisory
Ubuntu 18.04 (ESM)	`mongodb`	fixed	`1:3.6.3-0ubuntu1.4+esm2`
Ubuntu 20.04 (ESM)	`mongodb`	fixed	`1:3.6.9+really3.6.8+90~g8e540c0b6d-0ubuntu5.3+esm1`
Ubuntu 20.04 LTS (ESM)	`mongodb`	fixed	`1:3.6.9+really3.6.8+90~g8e540c0b6d-0ubuntu5.3+esm1 (USN-8160-1)`
Ubuntu 18.04 LTS (ESM)	`mongodb`	fixed	`1:3.6.3-0ubuntu1.4+esm2 (USN-8160-1)`

From the Debian security tracker, Ubuntu CVE tracker and Red Hat Security Data API, refreshed every few hours.

If you cannot patch yet

If you cannot upgrade, disable zlib by starting mongod/mongos with networkMessageCompressors (or net.compression.compressors in mongod.conf) set to a list without zlib, e.g. snappy,zstd or disabled (MongoDB).

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.

This vulnerability could affect an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: https://jira.mongodb.org/browse/SERVER-115508 ; https://nvd.nist.gov/vuln/detail/CVE-2025-14847

Sources

Page generated automatically from official sources on 2026-11-03 18:05 UTC and reviewed by an editor. Always confirm with your vendor's advisory.