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HighVulnerabilityupdated 30 Oct 2026, 14:17 UTC

Bouncy Castle for Java: several security flaws can be exploited

Bouncy Castle is a Java library that programs use for encryption. Attackers can exploit several flaws in it to bypass security checks, read or change data, or crash the software.

Official source
SeverityHighVulnerability
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official sourceBacked by an official source

What happened

Multiple vulnerabilities in the Bouncy Castle cryptographic library for Java allow privilege escalation, security bypass, data manipulation or disclosure, and denial of service.

Why it is dangerous: A remote, anonymous attacker can trigger these flaws without logging in, which can expose sensitive information or take down services that depend on the library.

Are you affected?

You are affected if you run Java applications that use Bouncy Castle for Java in any version the BSI advisory marks as vulnerable.

Bouncy Castle for Java (exact versions not stated in the provided material)

What to do

  1. Check whether your Java applications include Bouncy Castle and which version
  2. Update Bouncy Castle for Java to the fixed version named in the vendor advisory
  3. Restart affected applications after updating

Timeline

  1. 30 Oct 2026, 10:48 UTC
    Publicly disclosed
  2. 30 Oct 2026, 10:48 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  3. 30 Oct 2026, 10:48 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  4. 30 Oct 2026, 10:50 UTC
    Picked up by Zero Radar
  5. 30 Oct 2026, 14:17 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)

Sources 3 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
ZR-50b40611 · ZR-747d82f0
Disclosed
30 Oct 2026, 10:48 UTC
On Zero Radar
30 Oct 2026, 10:50 UTC (2 min after disclosure)
Last change
30 Oct 2026, 14:17 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Bouncy Castle for Java: several security flaws can be exploited · Zero Radar