---
id: CVE-2026-63570
title: >-
  Loop with unreachable exit condition in Pkcs12Store.GetCertificateChain in
  Legion of the Bouncy Castle Inc
summary: >-
  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 ke…
severity: high
cvss: 7.1
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'
cwe:
  - CWE-835
vendor: Legion of the Bouncy Castle Inc.
product: BouncyCastle.Cryptography
affected:
  - BouncyCastle.Cryptography < 2.7.0
published: '2026-10-02'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T08:17:01.833'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63570'
references:
  - url: >-
      https://github.com/bcgit/bc-csharp/commit/1b8fad04df4953230c9951c57678ee45c8aead85
    label: 91579145-5d7b-4cc5-b925-a0262ff19630
  - url: 'https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63570'
    label: 91579145-5d7b-4cc5-b925-a0262ff19630
tags:
  - nvd
  - cve.org
cvssSource: cna
ingestedAt: '2026-10-02T08:14:06.229Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.