CVE-2026-103604: legion of the bouncy castle inc. bc-csharp Inefficient Algorithmic Complexity

Vulnerability summary

CVE-2026-103604 is a high (CVSS 8.7) Inefficient Algorithmic Complexity vulnerability in legion of the bouncy castle inc. bc-csharp. EPSS estimates a 0.26% chance of exploitation in the next 30 days, higher than 16.5% of scored vulnerabilities.

Timeline

1. 02-10-2026
   PublishedVulnerability first disclosed.
2. 02-10-2026
   Last modifiedVulnerability information updated.

Description

Inefficient algorithmic complexity in X.509 distinguished name string conversion (X509Name.ToString and IetfUtilities.ValueToString) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote unauthenticated attacker to cause a denial of service through CPU exhaustion via a certificate, CRL, certification request or other structure whose name contains a long attribute value made up of characters that must be escaped, such as commas, or of leading or trailing spaces, because each escaping backslash was inserted into the buffer being scanned, so the work grew quadratically with the length of the value. Applications are exposed when they convert such a name to a string, for example to log or display it, or compare it with IetfUtilities.RdnAreEqual, as PKIX path validation does for directoryName name constraints.

• CWE-407Inefficient Algorithmic ComplexityAn algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.