CVE-2026-118383: MongoDB crash or RCE in replication

Summary

A use-after-free flaw in the replication component of MongoDB Server, affecting replica set members (including shard and config server members in sharded clusters but not standalone instances), can let an attacker crash the server or, under certain conditions, run arbitrary code. It can be reached remotely over the network, without logging in, by sending requests that need no authentication when a newly elected primary finishes catch-up.

Written by anthropic/claude-sonnet-5.5 from the sources below. Verify against them.

Read the original description

A use-after-free in the replication component of MongoDB Server can occur when a newly elected replica set primary completes catch-up. The condition can be caused by requests that do not require authentication, and may result in the server terminating unexpectedly or, under certain conditions, arbitrary code execution in the context of the server process. Replica set members are affected, including the shard and config server replica set members of sharded clusters; standalone mongod instances are not.

cve.now Index

44Pcve.now Index 44 of 100 · methodology v3 · provisional

Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
Reach17/20Affects MongoDB (a widely deployed server, runtime, framework or database)
Severity9.5/10CVSS 9.5
No patch0/5No signal

What would change the score

Would score about 89 if added to CISA KEV
Would score about 84 if CISA's SSVC rates exploitation active
Would score about 49 if advisories confirm default setups are exposed

How the score works · Rankings

What to do

Upgrade to a fixed version: 9.0.7, 8.3.16, 8.0.37, 7.0.48, 6.0.30, or one of 2 more.

Check your systems with an agent

Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.

Check whether my systems are affected by CVE-2026-118383 (Pre-authentication use-after-free in MongoDB Server replica set primary catch-up), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-118383 (entry last updated 2026-11-10):
Affected:
- MongoDB MongoDB Server: from 9.0.0, fixed in 9.0.7; from 8.3.0, fixed in 8.3.16; from 8.0.0, fixed in 8.0.37; from 7.0.0, fixed in 7.0.48; from 6.0.0, fixed in 6.0.30; from 5.0.0, fixed in 5.0.35; from 4.4.0, fixed in 4.4.32
Fixed versions: 9.0.7, 8.3.16, 8.0.37, 7.0.48, 6.0.30, 5.0.35, 4.4.32.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-118383 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-118383 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://jira.mongodb.org/browse/SERVER-138119
- https://jira.mongodb.org/browse/SERVER-138175
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Entry: https://cve.now/CVE-2026-118383
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-118383.

Timeline

Nov 10, 2026, 8:23 PM UTCCVE published
Nov 10, 2026, 9:26 PM UTCFirst seen by cve.now
Nov 10, 2026, 9:49 PM UTCPosted on X by cve.now

Affected versions

MongoDB MongoDB Server
From 9.0.0 · fixed in 9.0.7; From 8.3.0 · fixed in 8.3.16; From 8.0.0 · fixed in 8.0.37; From 7.0.0 · fixed in 7.0.48; From 6.0.0 · fixed in 6.0.30; From 5.0.0 · fixed in 5.0.35; From 4.4.0 · fixed in 4.4.32

Evidence 4

Vendor advisory · 2

Establishes: Affected and fixed versions.

CVE record · 2

Establishes: The identifier and description.

Record
CVE List · CVE-2026-118383
Record
NVD · CVE-2026-118383

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-118383

Is CVE-2026-118383 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

Which versions are affected by CVE-2026-118383?

MongoDB Server: from 9.0.0 before 9.0.7; from 8.3.0 before 8.3.16; from 8.0.0 before 8.0.37; from 7.0.0 before 7.0.48; from 6.0.0 before 6.0.30; from 5.0.0 before 5.0.35; from 4.4.0 before 4.4.32.Source: cve.now feed data

How do I fix CVE-2026-118383?

Upgrade to the fixed release for the branch in use: 4.4.32, 5.0.35, 6.0.30, 7.0.48, 8.0.37, 8.3.16 or 9.0.7. No workaround is listed in the facts.Source: jira.mongodb.org

Why do the sources disagree?

The description describes the issue as requiring authentication, while the CVSS vector records privileges required as none (PR:N). The sources do not resolve which is correct.Source: jira.mongodb.org

Pre-authentication use-after-free in MongoDB Server replica set primary catch-up