CVE-2026-96748 Connection redirection via percent-encoded delimiter injection in connection string hosts
Attackers can inject percent-encoded delimiters in connection strings to redirect database traffic to malicious servers, allowing observation and alteration of data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-96748?
CVE-2026-96748 is a high-severity server-side request forgery vulnerability in MongoDB Python Driver, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
PyMongo's connection string parsing decodes percent-encoded characters in the host portion before the host list is separated on its delimiters. When an application places a hostname value supplied by an unauthenticated party into a connection string, that party may cause additional servers of their choosing to be added to the application's database client. The application may then send its authentication exchange and database operations to one of those servers, which can observe limited information and return altered results.
Weakness: CWE-177
Which versions are affected by CVE-2026-96748?
3 open source packages ship an affected version, including pymongo.
| Package | Affected | Fixed in |
|---|---|---|
pymongo PyPI | From 3.5.0 | 4.18.2 |
pymongo PyPI | From 3.5.0 | 4.18.2 |
pymongo PyPI | From 3.5.0 | 4.18.2 |
How do I fix CVE-2026-96748?
Upgrade pymongo to 4.18.2 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-96748 being exploited?
There is no known exploitation of CVE-2026-96748 in the wild and no public exploit code.
Sources
Also known as AZL-105107, DEBIAN-CVE-2026-96748, ECHO-130e-9a6b-8aff, GHSA-vp6j-j7w5-5xjj, MINI-gqc7-xmpr-w538, PYSEC-2026-4297 and 2 more.