7.1

CVE-2026-9749: mongodb Reachable Assertion

CVSS: 7.1v4.0HighAnalyzed
AliasesUBUNTU-CVE-2026-9749
Published 09-06-2026Last modified 10-06-2026
Open JSON

Vulnerability summary

CVE-2026-9749 is a high (CVSS 7.1) Reachable Assertion vulnerability in mongodb. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39.3% of scored vulnerabilities.

Overall risk
28/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.1/10
010
High · v4.0 (CVE.org)
EPSS score
0.47%
0%100%
Low · +0.20 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 09-06-2026
    PublishedVulnerability first disclosed.
  2. 10-06-2026
    Last modifiedVulnerability information updated.

Description

This issue can occur when running an aggregation pipeline that uses the internal $exchange stage configured with key-range partitioning and order-preserving delivery. If a single key range produces enough documents to fill its exchange buffer (that is, many results are routed to the same consumer), the server reaches the code path where a full per-consumer buffer is detected but the internal "high watermark" for that key range is not updated as intended.

CVSS metrics

6 scores · 3 sources · 2 versions

EPSS trend

Probability

0.47%

Chance of exploitation in the next 30 days

Percentile

39%

Versus all other CVEs

30-day change

+0.20 pp

From 0.27% on 18-09-2026

18-09-202618-10-2026
EPSS score
0.47%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Mongodb2 products
  • mongodb≥ 7.0.0, < 7.0.35 | ≥ 8.0.0, < 8.0.24 | ≥ 8.2.0, < 8.2.10 | ≥ 8.3.0, < 8.3.3
  • mongodb server≥ 8.3.0, < 8.3.3 | ≥ 8.2.0, < 8.2.10 | ≥ 8.0.0, < 8.0.24 | ≥ 7.0.0, < 7.0.35
Ubuntu1 product
  • mongodbAll versions (No fix recorded)

2 vendors · 3 products

References

3 links