CVE-2026-59645 in Bouncy Castle for Java FIPS
Summary
by MITRE • 08/03/2026
In Bouncy Castle for Java before 1.85, OER parser recurses without depth limit on self-referential IEEE 1609.2 schema. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcutil-fips 2.0.7 (2.0.X series) and 2.1.7 (2.1.X series).
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/03/2026
The vulnerability in Bouncy Castle for Java represents a critical stack overflow condition that arises from improper handling of recursive data structures within the OER (Octet Encoding Rules) parser implementation. This flaw specifically manifests when processing self-referential IEEE 1609.2 schema definitions, which are commonly used in automotive and transportation security applications. The absence of depth limiting mechanisms during recursive parsing operations creates an exploitable condition that can lead to application crashes or denial of service scenarios.
The technical root cause stems from the parser's inability to enforce recursion limits when encountering circular references within the schema structure. IEEE 1609.2 defines cryptographic message syntax for automotive applications and includes complex nested structures that may reference themselves, creating potential infinite loops during parsing operations. The OER parser in affected versions lacks proper depth tracking and maximum recursion limits, allowing maliciously crafted input to exhaust stack memory resources through unbounded recursive calls.
This vulnerability impacts a broad range of Bouncy Castle implementations including the standard Java library, Long Term Support releases, and FIPS certified variants. The affected versions demonstrate a pattern of insufficient input validation that violates fundamental security principles for parsing operations. According to CWE-674, this represents an uncontrolled recursion flaw where the system fails to prevent excessive recursive calls that could lead to resource exhaustion. The vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks through resource exhaustion.
The operational impact extends beyond simple application crashes to potentially enable more sophisticated attack vectors in environments where Bouncy Castle is used for cryptographic operations. Systems processing security certificates, encrypted communications, or automotive data exchanges may become unavailable when encountering malformed IEEE 1609.2 schemas. The vulnerability affects critical infrastructure components including automotive security systems, transportation protocols, and any application relying on Bouncy Castle's OER parsing capabilities for handling standardized cryptographic messages.
Mitigation strategies should prioritize immediate version upgrades to patched releases including Bouncy Castle Java 1.85, LTS 2.73.12, and FIPS variants with proper recursion limits. Organizations should implement input validation measures to detect and reject malformed schemas before they reach the parser stage. Additionally, runtime monitoring for stack overflow conditions and implementing maximum recursion depth parameters within application configurations can provide additional defense layers. System administrators should also consider network segmentation and access controls to limit exposure of vulnerable applications to untrusted input sources while maintaining compliance with industry standards such as NIST SP 800-53 and ISO 27001 requirements for secure coding practices.