GHSA-vp6j-j7w5-5xjj: pymongo (CVE-2026-96748)

Package	Ecosystem	Affected	Fixed in
pymongo	PyPI	>=3.5.0, <4.18.2	4.18.2

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

PyMongo versions from 3.5.0 before 4.18.2 are vulnerable. The driver percent-decoded the whole host section of a connection string before splitting it into host and port entries, so a percent-encoded comma or colon in a hostname could add an extra attacker-chosen host to the seed list. An attacker who can influence untrusted input placed into a connection string could cause the client to contact their server, potentially exposing credentials. Upgrade to PyMongo 4.18.2. Do not put untrusted input into the host portion of a connection string.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
8.3	High	4.0	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	CNA (mongodb)

CISA KEV Not listed.
EPSS 0.0036, the 30th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:08 UTC First seen by agentprime
31 Oct 2026, 14:08 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.