Bouncy Castle bc-csharp up to 2.6.x Certificate Chain Building Pkcs12Store.GetCertificateChain infinite loop

Summaryinfo

A vulnerability marked as problematic has been reported in Bouncy Castle bc-csharp up to 2.6.x. Impacted is the function Pkcs12Store.GetCertificateChain of the component Certificate Chain Building. This manipulation causes infinite loop. This vulnerability is handled as CVE-2026-63570. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Bouncy Castle bc-csharp up to 2.6.x. Affected by this vulnerability is the function Pkcs12Store.GetCertificateChain of the component Certificate Chain Building. The manipulation with an unknown input leads to a infinite loop vulnerability. The CWE definition for the vulnerability is CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. As an impact it is known to affect availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-63570 since 07/17/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 2.7.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-3713). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Open Source Bouncy Castle

Productinfo

Vendor

• Bouncy Castle

Name

• bc-csharp

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6

CPE 2.3info

• 🔒
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CPE 2.2info

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Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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