CVE-2021-41119

Wire-server is the system server for the wire back-end services. Releases prior to v2022-03-01 are subject to a denial of service attack via a crafted object causing a hash collision. This collision causes the server to spend at least quadratic time parsing it which can lead to a denial of service for a heavily used server. The issue has been fixed in wire-server 2022-03-01 and is already deployed on all Wire managed services. On premise instances of wire-server need to be updated to 2022-03-01, so that their backends are no longer affected. There are no known workarounds for this issue.

Weakness

The product does not properly control the allocation and maintenance of a limited resource.

Affected Software

Potential Mitigations

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• https://cs-syd.eu/posts/2021-09-11-json-vulnerability
• https://github.com/wireapp/wire-server/security/advisories/GHSA-phxv-pffh-fq2r
• https://cs-syd.eu/posts/2021-09-11-json-vulnerability
• https://github.com/wireapp/wire-server/security/advisories/GHSA-phxv-pffh-fq2r