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CVE-2021-41100


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.


Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.4, indicating it can be exploited remotely over the network but requires specific conditions to be met without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), for affected systems. Impacting 1 product from wire organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2021-10-04T19:15:08.510

Last Modified

2024-11-21T06:25:28.137

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 7.4 (HIGH)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:P/I:P/A:P

  • Access Vector: NETWORK
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: PARTIAL
  • Integrity Impact: PARTIAL
  • Availability Impact: PARTIAL
Exploitability Score

10.0

Impact Score

6.4

Weaknesses
  • Type: Secondary
    CWE-285
  • Type: Primary
    CWE-613

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application wire wire-server < 2021-08-16 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For wire's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.