CVE-2026-71883
Native AES packet cipher returns the raw AES key on an alias
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.
INFO
Published Date :
Oct. 3, 2026, 9:17 a.m.
Last Modified :
Oct. 3, 2026, 9:17 a.m.
Remotely Exploit :
Yes !
Source :
91579145-5d7b-4cc5-b925-a0262ff19630
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | HIGH | 91579145-5d7b-4cc5-b925-a0262ff19630 | ||||
| CVSS 4.0 | HIGH | 91579145-5d7b-4cc5-b925-a0262ff19630 |
Solution
- Update Bouncy Castle for Java LTS to version 2.73.13.
- Apply vendor patches for affected native packet ciphers.
- Verify JNI ReleaseByteArrayElements usage.
- Avoid in-place encryption with critical data.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-71883.
| URL | Resource |
|---|---|
| https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071883 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-71883 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-71883
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-71883 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-71883 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 91579145-5d7b-4cc5-b925-a0262ff19630
Oct. 03, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber Added CWE CWE-200 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/71xxx/CVE-2026-71883.json">CVE-2026-71883</a> Added Reference https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071883