The vulnerability arises from a quadratic time complexity in processing X.509 distinguished name strings when escaping certain characters like commas or spaces. Each escaping backslash is inserted into the buffer being scanned, causing the processing time to grow quadratically with the length of the attribute value. This can be exploited remotely by an unauthenticated attacker by supplying a certificate, CRL, or certification request with a specially crafted name, resulting in CPU exhaustion and denial of service. The affected methods are X509Name.ToString and IetfUtilities.ValueToString in bc-csharp versions prior to 2.7.0. Applications that convert these names to strings, such as during logging or PKIX path validation, are vulnerable.

An attacker can cause a denial of service by exhausting CPU resources through supplying a crafted certificate or related structure with a long attribute value requiring escaping. This impacts availability of applications using vulnerable versions of bc-csharp when they process such names. No authentication or user interaction is required, and the attack surface includes any application converting X.509 distinguished names to strings using the affected methods.

Upgrade to bc-csharp version 2.7.0 or later, where this inefficient algorithmic complexity issue is fixed. No other mitigation is indicated. Patch status is confirmed by the version boundary provided. There is no indication of temporary fixes or vendor advisories stating otherwise.