CVE-2026-118669
Description
A flaw was found in oauthlib. In certain token grant flows, the authorization system can authenticate an incoming client while retaining a different, client-supplied identifier for permission and scope validation. A remote, authenticated attacker with lower privileges can exploit this inconsistency by submitting another client's identifier during token requests. This flaw leads to privilege escalation, potentially allowing the attacker to obtain access tokens with unauthorized permissions and scopes associated with another client.
Statement
This vulnerability is rated as an Important severity for Red Hat products because an authenticated client with low privileges can obtain access tokens under a different identity over the network, leading to significant privilege escalation without requiring user interaction. The exposure specifically impacts deployments where the server application relies on the submitted client identifier parameter during scope or grant checks instead of the authenticated client object. Workloads that do not act as an OAuth2 token endpoint or that enforce scope authorization solely from the authenticated entity remain unaffected.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | High | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
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