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CVE-2026-71883— Native AES packet cipher returns the raw AES key on an alias

Quick assessment

Affected
Legion of the Bouncy Castle Inc. BC-LTS-JAVA
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Java 长期支持版本（LTS）中，Bouncy Castle 在 2.73.13 版本之前存在一个漏洞：AES-CBC、CCM、CFB、CTR、GCM 和 GCM-SIV 的一次性原生包密码（native packet ciphers）在使用 JNI 的 ReleaseByteArrayElements 方法时，以模式 0（mode 0）释放调用者传入的密钥（key）、初始化向量（IV）以及附加认证数据（additional authenticated data）数组。模式 0 会将原生内存副本写回 Java

CVSS 8.2 · High EPSS 0.25% · P15

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-71883

Vulnerability Information
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Vulnerability Title
Native AES packet cipher returns the raw AES key on an alias
Source: CVE Program / CVE List V5
Vulnerability Description
In Bouncy Castle for Java LTS before 2.73.13, the one-shot native packet ciphers for AES-CBC, CCM, CFB, CTR, GCM and GCM-SIV released the caller's key, IV and additional authenticated data arrays with JNI's ReleaseByteArrayElements in mode 0, which commits the native copy back into the Java array. Those arrays are read-only to the native code, and on a JVM that returns a copy rather than a pin the copy still holds the input bytes as they were read. The output buffer is taken through a separate critical region and committed first, so where an application passed the same Java array as both an input and the destination - encrypting in place over KeyParameter.getKey(), for example - the later mode-0 release of the key wrote the unchanged key bytes over the ciphertext that had just been produced. The call still returned the correct output length, so an application encrypting in place over its own key array was handed the raw AES key where it expected ciphertext, with nothing in the API to indicate it, and would transmit or store the key in place of the message. The read-only input arrays are now released with JNI_ABORT, freeing the native copy without copying it back, and mode 0 is reserved for arrays the native code wrote. The pure-Java packet ciphers and the streaming native modes are not affected. Bouncy Castle for Java (bcprov) is not affected, as it ships no native implementations.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/U:Amber
Source: CVE Program / CVE List V5
Vulnerability Type
信息暴露
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Legion of the Bouncy Castle Inc. BC-LTS-JAVA 2.73.4 ~ 2.73.13 -

II. Public POCs for CVE-2026-71883

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III. Intelligence Information for CVE-2026-71883

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Security Blog Posts for CVE-2026-71883 (1)

Same Patch Batch · Legion of the Bouncy Castle Inc. · 2026-10-03 · 12 CVEs total

CVE-2026-71885 9.2 CRITICAL MLS X.509 credential not bound to the LeafNode signature key
CVE-2026-71888 8.7 HIGH CMS AuthenticatedData exposes attacker-inserted authAttrs when digestAlgorithm is absent
CVE-2026-71889 8.7 HIGH PKIXCertPathReviewer does not apply X.509 name constraints to the target certificate
CVE-2026-71890 8.7 HIGH MLS external commit can remove an arbitrary group member
CVE-2026-85515 8.2 HIGH OpenPGP message truncation not reported, bypassing the SEIPDv1 integrity check
CVE-2026-71887 8.2 HIGH OpenPGP data signature accepted from a signing subkey without cross-certification
CVE-2026-71886 8.2 HIGH OpenPGP certification accepted from a subkey without certification authority
CVE-2026-71891 7.1 HIGH BLS12-381 key validation accepts a public key built on a foreign curve
CVE-2026-71892 6.9 MEDIUM CMS key-transport recipient key-size validation never runs for RFC 9709 HKDF-derived keys
CVE-2026-18040 5.9 MEDIUM HQC leaks private key information through secret-indexed GF(2^8) tables and a secret-depen
CVE-2026-97873 5.3 MEDIUM Legacy PBES1 and PKCS#12 PBE iteration count honoured unbounded in the raw JCA provider

IV. Related Vulnerabilities

Same vendor: Legion of the Bouncy Castle Inc.
Same weakness: CWE-200

V. Comments for CVE-2026-71883

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