CVE-2026-63570: Legion Of The Bouncy Castle Inc Bc-Csharp

High severity, CVSS 7.1. EPSS: 0.2% chance of exploitation in the next 30 days.

Loop with unreachable exit condition in Pkcs12Store.GetCertificateChain in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who can supply a crafted PKCS#12 file to an application that loads it and requests a key entry's certificate chain to cause a denial of service, in which the call never returns and consumes CPU and memory until an OutOfMemoryException, via certificates whose issuer links form a cycle, for example two certificates whose AuthorityKeyIdentifier extensions each identify the other's public key. This happens because the chain-building loop stops only when no issuer is found or a certificate links to itself, and keeps no record of certificates already visited. The key-identifier links are followed without checking signatures.

Affected products

• Legion Of The Bouncy Castle Inc Bc-Csharp: before 2.7.0 (fixed in 2.7.0)

Published 2026-10-02. Last modified 2026-10-02.