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VulnerabilityPublished

CVE-2026-96748: MongoDB Python Driver · Improper Handling of URL Encoding

Affects MongoDB Python DriverSource CVE Database V5

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Not known to be exploited · CVSS 8.3 High : upgrade to 4.18.2 soon.

Data as of 6 Nov 2026, 23:24 UTC

CVSS 4.0 base score
8.3High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.18.2
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

What to do

Upgrade Python Driver and pymongo to 4.18.2.

Affected software

ProductAffectedFixed in
MongoDBPython DriverAffected
  • <4.18.2
Fixed in
  • 4.18.2
PyPIpymongopkg:pypi/pymongoOther threatsAffected
  • <4.18.2
Fixed in
  • 4.18.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, applications should avoid incorporating untrusted or unauthenticated hostname values into MongoDB connection strings to prevent injection of malicious hosts.

Description

CVE-2026-96748 is a vulnerability in the PyMongo Python driver for MongoDB where improper handling of URL encoding in connection strings can allow an attacker to inject additional servers into the client's host list. This occurs because percent-encoded characters in the host portion are decoded before splitting the host list, enabling an unauthenticated party to manipulate the connection string. As a result, the application may send authentication and database operations to attacker-controlled servers, which can observe limited information and return altered results. The issue affects PyMongo versions from 0 up to but not including 4.18.2.

References

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