CVE-2021-41101: CORS `Access-Control-Allow-Origin` settings are too lenient

Severity: low (CVSS 3.5 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-09-30 · updated 2026-06-17
Weakness: CWE-79

Description

wire-server is an open-source back end for Wire, a secure collaboration platform. Before version 2.106.0, the CORS ` Access-Control-Allow-Origin ` header set by `nginz` is set for all subdomains of `.wire.com` (including `wire.com`). This means that if somebody were to find an XSS vector in any of the subdomains, they could use it to talk to the Wire API using the user's Cookie. A patch does not exist, but a workaround does. To make sure that a compromise of one subdomain does not yield access to the cookie of another, one may limit the `Access-Control-Allow-Origin` header to apps that actually require the cookie (account-pages, team-settings and the webapp).

Affected products

wireapp wire-server: before 2.106.0 — fixed in 2.106.0

How to fix

Upgrade to a fixed version: wireapp wire-server 2.106.0. Check the vendor advisory for mitigations.

References

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