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Account hijacking through oauth2

High
alextran1502 published GHSA-3832-6r8h-9cfm Jul 11, 2025

Package

docker immich-server (docker)

Affected versions

< v1.132.0

Patched versions

>= v1.132.0

Description

Summary

immich is vulnerable to account hijacking through oauth2, because the state parameter is not being checked.

Details

the oauth2 state parameter is similar to a csrf token, so when the user starts the login flow this unpredictable token is generated and somehow saved in the browser session and passed to the identity provider, which will return the state paramter when redirecting the user back to immich. before the user is logged in that parameter needs to be verified to make sure the login was actively initiated by the user in this browser session.

on it's own, this wouldn't be too bad, but when immich uses the /user-settings page as a redirect_uri, it will automatically link the accounts if the user was already logged in. This means that if someone has an immich instance with a public oauth provider (like google), an attacker can - for example - embed a hidden iframe in a webpage or even just send the victim a forged oauth login url with a code that logs the victim into the attackers oauth account and redirects back to immich and links the accounts. after this, the attacker can log into the victims account using their own oauth credentials.

PoC

Assuming an immich instance at https://immich.example.com and oauth at https://login.example.com and a user with email [email protected] and a user with email [email protected] that has an account at https://login.example.com, the attacker can initiate the oauth flow by opening https://login.example.com/ui/oauth2?client_id=immich&scope=openid%20email%20profile&response_type=code&redirect_uri=https%3A%2F%2Fimmich.example.com%2Fuser-settings&state=gibberish, note that state=gibberish is a valid state parameter, because the one generated by the immich web app - while being unpredictable, as it should be - does not do anything. The attacker now logs in on https://login.example.com, but does not allow the redirect back to immich on their end (various methods to do this without much effort, for example blocking the immich.example.com domain on their own machine for the purpose of the exploit), the oauth flow tries to send them back to immich by redirecting to https://immich.example.com/user-settings?code=<code>&state=gibberish. They can set up a script to generate these urls continously and send them to users by hiding them behind url shorteners, but they can also embed the url in a (hidden) iframe on a website they control that the user visits ("hey, I made this tool for immich that allows you to do xyz, take a look at demo.attacker.com"). When the url is loaded in the browser of a logged in user, their account gets linked to the attacker's account.

Impact

All immich instances with publicly accessible oauth2 providers (google, etc) are affected. This likely includes most instances set up with cloudflare access that people consider private-ish, unless they have some additional rules like an account/email whitelist. In theory, if you don't trust your friends then private instances are affected as well in a way. If the attacker manages to hijack an admin account this way, they could change the oauth instance to one they control and start logging into arbitrary accounts and lock out the admin by disabling password login and deleting all other sessions via settings. The admin would need to take back control using the host system. (While I have confirmed the PoC described earlier I have not explored the further paths just mentioned)

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required Low
User interaction Active
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability High
Subsequent System Impact Metrics
Confidentiality High
Integrity High
Availability High

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVE ID

CVE-2025-43856

Weaknesses

Incorrect Implementation of Authentication Algorithm

The requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect. Learn more on MITRE.

Credits