# CVE-2026-71883: Bouncy Castle Java LTS native AES cipher key disclosure on array aliasing

Source: https://junglewise.ai/threats/cve-2026-71883-in-bouncy-castle-for-java-lts-before-2-73-13-the-one-shot-native  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-03. Updated: 2026-10-05  
License: CC BY 4.0 with a link back

CVE-2026-71883 · Severity: info · Published 2026-10-03

Bouncy Castle for Java LTS, a widely-used cryptography library, contains a bug in its native implementations of AES encryption that causes encryption-in-place operations to overwrite ciphertext with the raw encryption key. Applications that encrypt data directly into their own key array instead of a separate output buffer will accidentally expose the encryption key in place of the encrypted message, potentially transmitting or storing sensitive key material.

Technologies: [Bouncycastle Bouncy Castle For Java Lts](https://junglewise.ai/threats/technologies/bouncy-castle-for-java-lts). Vendors: [Bouncycastle](https://junglewise.ai/threats/vendors/bouncycastle).

## Quick answers

**Is CVE-2026-71883 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-71883 being exploited in the wild.

**How severe is CVE-2026-71883?** Informational severity, published 3 October 2026.

**Which products and versions are affected?** Bouncycastle Bouncy Castle For Java Lts before 2.73.13 (affected from 2.73.4).

**Is there a fix for CVE-2026-71883?** Yes: fixed in Bouncy Castle for Java LTS 2.73.13. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-71883 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-71883?** Check whether you run Bouncycastle Bouncy Castle For Java Lts at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Bouncy Castle for Java LTS 2.73.13

## Technical details

The native packet ciphers for AES-CBC, CCM, CFB, CTR, GCM and GCM-SIV in Bouncy Castle Java LTS (versions 2.73.4 through 2.73.12) use JNI to perform encryption but incorrectly release input arrays (including keys and IVs) in read-write mode, allowing stale copies to overwrite the output buffer. When an application passes the same Java array as both input and output—such as encrypting directly into a KeyParameter.getKey() array—the output buffer is committed first, then the unchanged key bytes are committed over the ciphertext. The pure-Java implementations and streaming native modes are unaffected, as are regular Bouncy Castle distributions without native code.

## Affected products

- Bouncycastle Bouncy Castle for Java LTS before 2.73.13 (affected from 2.73.4)

## Timeline

- 2026-10-03: disclosed

## References

- [https://www.bouncycastle.org/download/bouncy-castle-java-lts/](https://www.bouncycastle.org/download/bouncy-castle-java-lts/)
- [https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071883](https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071883)

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