---
title: "CVE-2026-71884: Bouncy Castle - Cryptographic Vulnerability"
description: "Bouncy Castle for Java LTS before 2.73.13 contains a cryptographic vulnerability caused by lack of counter range validation in native one-shot CTR packet cipher, letting attackers recover plaintext from ciphertext due to keystream reuse, exploit requires crafted input with specific IV length."
url: https://panop.io/threat-heartbeat/CVE-2026-71884/
---

# CVE-2026-71884 Bouncy Castle - Cryptographic Vulnerability

Bouncy Castle for Java LTS before 2.73.13 contains a cryptographic vulnerability caused by lack of counter range validation in native one-shot CTR packet cipher, letting attackers recover plaintext from ciphertext due to keystream reuse, exploit requires crafted input with specific IV length.

CVSS base score 8.2 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.41% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-71884)

## Details

Type

Cryptographic Vulnerability

Impact

Information Disclosure

CVSS vector

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/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

Published

9 October 2026

Updated

15 October 2026

Weakness

[CWE-323](https://cwe.mitre.org/data/definitions/323.html)

## Vendor fix

Update to version 2.73.13 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-71884](https://nvd.nist.gov/vuln/detail/CVE-2026-71884)
- [https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071884](https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071884)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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