CVE-2026-15997 in BC-LTS
Summary
by MITRE • 07/17/2026
Out-of-bounds write vulnerability in Legion of the Bouncy Castle Inc. BC-LTS bcprov-lts8on on ARM allows Overflow Buffers.
This vulnerability is associated with program files https://github.Com/bcgit/bc-lts-java/blob/main/native_c/arm/sha/shake.C, https://github.Com/bcgit/bc-lts-java/blob/main/native_c/arm/sha/sha3.C.
This issue affects BC-LTS: from 2.73.0 before 2.73.12.1.
Issue is only applicable if application involved is accepting memoable SHA3 / SHAKE states from potentially untrusted sources.
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Analysis
by VulDB Data Team • 07/17/2026
The vulnerability under examination represents a critical out-of-bounds write condition within the Bouncy Castle cryptographic library implementation specifically targeting ARM architecture systems. This flaw manifests in the native C code components responsible for SHA3 and SHAKE hash computations, where improper bounds checking allows malicious data to overwrite adjacent memory regions. The affected component resides in the bcprov-lts8on library version 2.73.0 through 2.73.12.0, creating a window of exposure for applications that process potentially untrusted cryptographic states from external sources. The vulnerability stems from insufficient input validation when handling memoable SHA3/SHAKE state objects, which are designed to maintain internal cryptographic context for continued computation.
The technical exploitation of this vulnerability occurs through manipulation of cryptographic state data structures during SHA3 or SHAKE algorithm execution on ARM processors. When applications accept memoable state objects from untrusted sources without proper validation, the underlying C implementation fails to verify array bounds before writing data to memory locations. This condition falls under CWE-787, specifically an out-of-bounds write vulnerability that can result in arbitrary code execution or system compromise. The ARM-specific nature of this flaw means that the exploitation vector is limited to systems running on ARM architecture while maintaining the same underlying memory layout issues present in the native implementation.
The operational impact of this vulnerability extends beyond simple data corruption, as it creates potential pathways for privilege escalation and remote code execution within applications leveraging affected Bouncy Castle versions. Attackers who can supply malicious memoable SHA3/SHAKE state data can cause buffer overflows that may overwrite critical program variables, function pointers, or return addresses, enabling arbitrary code execution with the privileges of the running application. This vulnerability directly aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1547.001 for registry run keys, as exploitation could lead to persistent backdoor installation through compromised cryptographic processes. Systems using this library for secure communications, digital signature validation, or authentication mechanisms face heightened risk of complete system compromise.
Mitigation strategies should prioritize immediate version upgrades to BC-LTS 2.73.12.1 or later, which contain fixed implementations addressing the buffer overflow conditions in the ARM native code components. Organizations should also implement strict input validation for all cryptographic state objects received from external sources, utilizing sandboxing techniques and memory corruption detection mechanisms. Network segmentation and application whitelisting can limit potential attack surface exposure while monitoring systems should be deployed to detect anomalous cryptographic processing patterns indicating exploitation attempts. The fix addresses the root cause by implementing proper bounds checking in the sha/shake.C and sha3.C files, ensuring that all memory writes remain within allocated buffer boundaries regardless of input data characteristics. Security teams must also conduct thorough code reviews of any custom applications utilizing Bouncy Castle libraries to identify potential indirect exploitation paths through improper cryptographic state handling practices.