CVE-2024-45042

EUVD-2024-2888 · Published Sep 26, 2024

Ory Kratos's setting required_aal highest_available does not properly respect code + mfa credentials

Preconditions

The code login method is enabled with the passwordless_enabled flag set to true .
A 2FA method such as totp is enabled.
required_aal of the whomai check or the settings flow is set to highest_available. AAL stands for Authenticator Assurance Levels and can range from 0 (no factor) to 2 (two factors).
A user uses the code method as the only login method available. They do not have a password or any other first factor credential enabled.
The user has 2FA enabled.
The user’s available_aal is incorrectly stored in the database as aal1 or aal0 or NULL.
A user signs in using the code method, but does not complete the 2FA challenge.

Example server configuration

Below you will find an vulnerable example configuration. Keep in mind that, for the account to be vulnerable, the account must have no first factor except the code method enabled plus a second factor.

selfservice:
  methods:
    code:
      # The `code` login method is enabled with the `passwordless_enabled` flag set to `true`
      passwordless_enabled: true
    totp:
      # 2FA method such as `totp` is enabled
      enabled: true
  flows:
    settings:
      # This is set
      required_aal: highest_available
session:
  whoami:
    # Or this
    required_aal: highest_available

Impact

Given the preconditions, the highest_available setting will incorrectly assume that the identity’s highest available AAL is aal1 even though it really is aal2. This means that the highest_available configuration will act as if the user has only one factor set up, for that particular user. This means that they can call the settings and whoami endpoint without a aal2 session, even though that should be disallowed.

An attacker would need to steal or guess a valid login OTP of a user who has only OTP for login enabled and who has an incorrect available_aal value stored, to exploit this vulnerability.

All other aspects of the session (e.g. the session’s aal) are not impacted by this issue.

On Ory Network, only 0,00066% of registered users were affected by this issue, and most of those users appeared to be test users. Their respective AAL values have since been updated and they are no longer vulnerable to this attack.

Patches

Version 1.3.0 is not affected by this issue.

Workarounds

If you require 2FA please disable the passwordless code login method. If that is not possible, check the sessions aal to identify if the user has aal1 or aal2.

Technologies

Ory Kratos

Weaknesses

CWE-287

CVSS scores

v3.14.4CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access

T1190Exploit Public-Facing Application

References

Potentially impacted assets

See if this affects your attack surface

Latest trending attack

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Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.