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

> An attacker can obtain the raw AES key if an application encrypts data in place over the key array, due to incorrect JNI memory release in native ciphers.

- **Severity:** High 8.2 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Oct 2026
- **Updated:** 5 Oct 2026
- **Also known as:** GHSA-f5wg-4mfp-h458

## What is CVE-2026-71883?

CVE-2026-71883 is a high-severity vulnerability in Legion of the Bouncy Castle Inc. BC-LTS-JAVA, published on 3 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2026-71883?


## How do I fix CVE-2026-71883?

No fix has been published for CVE-2026-71883 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-71883 being exploited?

There is no known exploitation of CVE-2026-71883 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-71883 and fix it if it is affected.

What it is: CVE-2026-71883 is a high-severity vulnerability in Legion of the Bouncy Castle Inc. BC-LTS-JAVA, published on 3 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-71883 in the wild and no public exploit code.

Affected product: Legion of the Bouncy Castle Inc. BC-LTS-JAVA. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-71883/ (Markdown: https://insights.sbomify.com/CVE-2026-71883/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-71883
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-71883
- OSV: https://osv.dev/vulnerability/CVE-2026-71883

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-71883/
Summaries are generated and may contain mistakes; the official description above is the record.