CVE-2021-20201

A flaw was found in spice in versions before 0.14.92. A DoS tool might make it easier for remote attackers to cause a denial of service (CPU consumption) by performing many renegotiations within a single connection.

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://blog.qualys.com/product-tech/2011/10/31/tls-renegotiation-and-denial-of-service-attacks
• https://bugzilla.redhat.com/show_bug.cgi?id=1921846
• https://security.gentoo.org/glsa/202208-10
• https://blog.qualys.com/product-tech/2011/10/31/tls-renegotiation-and-denial-of-service-attacks
• https://bugzilla.redhat.com/show_bug.cgi?id=1921846
• https://security.gentoo.org/glsa/202208-10