CVE-2026-118669

What it is

OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. Prior to 4.0.0, the client_credentials and Resource Owner Password Credentials token grant handlers can authenticate request.client as one confidential client while retaining an attacker-supplied request.client_id for validate_grant_type and validate_scopes. A lower-privilege authenticated client can therefore cause grant and scope authorization to use another client's identity when an application validator relies on the documented client_id argument, potentially issuing tokens with unauthorized grants or scopes. Validators that authorize exclusively from request.client may not be affected. This issue is fixed in version 4.0.0.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data tampering.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-10-28 17:25 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-10-28 22:17 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-11-03 14:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.3% in the next 30 days (EPSS).
• Severity: 8.4 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-10-28 22:17 UTC

Last modified

2026-11-03 14:17 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-863 · Incorrect authorization

Record status

Awaiting Analysis

Attack profile CVSS 4.0 · 8.4

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

Low

User interaction

None

Confidentiality

None

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-118669.md and follow it. Check whether this project is affected by CVE-2026-118669. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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