What’s Vulnerable › Vulnerabilities

CVE-2019-1258: Azure Active Directory Authentication Library Elevation of Privilege Vulnerability

• Severity: high (CVSS 8.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-08-14 · updated 2026-06-17

Description

An elevation of privilege vulnerability exists in Azure Active Directory Authentication Library On-Behalf-Of flow, in the way the library caches tokens. This vulnerability allows an authenticated attacker to perform actions in context of another user. The authenticated attacker can exploit this vulneraiblity by accessing a service configured for On-Behalf-Of flow that assigns incorrect tokens. This security update addresses the vulnerability by removing fallback cache look-up for On-Behalf-Of scenarios.

Affected products

• Microsoft Active Directory Authentication Library: from 5.0.5 before 5.2.0; 5.0.0-preview, 5.0.1-preview, 5.0.2-preview, 5.0.3-preview — fixed in 5.2.0
• Microsoft Nuget: 5.2.0
• Microsoft ADAL.NET: from 5.0.0 before publication — fixed in publication
• Microsoft Nuget 5.2.0: from 5.0.0 before publication — fixed in publication

How to fix

Upgrade to a fixed version: Microsoft Active Directory Authentication Library 5.2.0; Microsoft ADAL.NET publication; Microsoft Nuget 5.2.0 publication. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1258
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1258

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