Microsoft Identity Denial of service vulnerability

Impact

What kind of vulnerability is it? Who is impacted?
An attacker could exploit this vulnerability by crafting a malicious JSON Web Encryption (JWE) token with a high compression ratio. This token, when processed by a server, leads to excessive memory allocation and processing time during decompression, causing a denial-of-service (DoS) condition.

It’s important to note that the attacker must have access to the public encrypt key registered with the IDP(Entra ID) for successful exploitation.

According to the CVSS metric, a successful exploitation could lead to a scope change (S:C). What does this mean for this vulnerability?
A scope change (S:C) in the CVSS metric indicates that successful exploitation of this vulnerability could extend beyond the immediate processing of malicious tokens, affecting the overall availability of the system by causing a denial-of-service (DoS) condition.

Patches

Has the problem been patched? What versions should users upgrade to?
The vulnerability has been fixed. Users should update all their Microsoft.IdentityModel versions to 7.1.2 (for 7x) or higher, 6.34.0 (for 6x) or higher, and 5.7.0 (for 5x).

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?
No, users must upgrade.

References

Are there any links users can visit to find out more?
https://aka.ms/IdentityModel/Jan2024/zip