Connection redirection via percent-encoded delimiter injection in connection string hosts (CVE-2026-96748) | HOL Guard CVE

High · CVSS 8.3CVE-2026-96748

Connection redirection via percent-encoded delimiter injection in connection string hosts

Answer in brief

CVE-2026-96748 records a High severity (CVSS 8.3) vulnerability in Connection redirection via percent-encoded delimiter injection in connection string hosts. The current sources do not mark it as known exploited. The current feed maps MongoDB/Python Driver (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 24, 2026Updated Sep 24, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 24, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 8.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps MongoDB/Python Driver (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
MongoDB/Python Drivergeneric	>=0 <4.18.2	4.18.2

Recommended response

Check inventory. Check lockfiles and deployed manifests for MongoDB/Python Driver.
Review the reported fix. Update MongoDB/Python Driver to 4.18.2 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.