CVE-2021-41100

What it is

Wire-server is the backing server for the open source wire secure messaging application. In affected versions it is possible to trigger email address change of a user with only the short-lived session token in the `Authorization` header. As the short-lived token is only meant as means of authentication by the client for less critical requests to the backend, the ability to change the email address with a short-lived token constitutes a privilege escalation attack. Since the attacker can change the password after setting the email address to one that they control, changing the email address can result in an account takeover by the attacker. Short-lived tokens can be requested from the backend by Wire clients using the long lived tokens, after which the long lived tokens can be stored securely, for example on the devices key chain. The short lived tokens can then be used to authenticate the client towards the backend for frequently performed actions such as sending and receiving messages. While short-lived tokens should not be available to an attacker per-se, they are used more often and in the shape of an HTTP header, increasing the risk of exposure to an attacker relative to the long-lived tokens, which are stored and transmitted in cookies. If you are running an on-prem instance and provision all users with SCIM, you are not affected by this issue (changing email is blocked for SCIM users). SAML single-sign-on is unaffected by this issue, and behaves identically before and after this update. The reason is that the email address used as SAML NameID is stored in a different location in the databse from the one used to contact the user outside wire. Version 2021-08-16 and later provide a new end-point that requires both the long-lived client cookie and `Authorization` header. The old end-point has been removed. If you are running an on-prem instance with at least some of the users invited or provisioned via SAML SSO and you cannot update then you can block `/self/email` on nginz (or in any other proxies or firewalls you may have set up). You don't need to discriminate by verb: `/self/email` only accepts `PUT` and `DELETE`, and `DELETE` is almost never used.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering.

Exploit odds

0.9% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-10-04 19:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:07 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.9% in the next 30 days (EPSS).
• Severity: 7.4 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-10-04 19:15 UTC

Last modified

2026-06-17 04:07 UTC

Exploit probability

0.9% · EPSS, next 30 days

Weakness

CWE-285

Record status

Modified

Affected

• Wire wire-server < 2021-08-16

Attack profile CVSS 3.1 · 7.4

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-41100.md and follow it. Check whether this project is affected by CVE-2021-41100. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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