CVE-2026-63572 Legion of the Bouncy Castle Inc. CVE debrief

Who should care

Defenders responsible for systems or applications using the Bouncy Castle Inc. bc-csharp library should assess exposure and prioritize patching or mitigation. This includes operators, platform administrators, vulnerability management teams, and security teams who need to verify affected versions and inventory checks required.

Why it matters

Defenders should care about CVE-2026-63572 because it allows an attacker to cause a denial of service through CPU exhaustion in the Bouncy Castle Inc. bc-csharp library before version 2.7.0. This vulnerability can be exploited by supplying a malicious PKCS#12 file, and defenders should prioritize patching or mitigation to prevent potential disruption to critical systems or services.

• Denial of service through CPU exhaustion
• Potential disruption to critical systems or services
• Need for patching or mitigation to prevent exploitation
• Verification of affected versions and inventory checks required

Technical summary

The Pkcs12Store.Load method in the Bouncy Castle Inc. bc-csharp library before version 2.7.0 does not properly handle iteration counts in PKCS#12 files, allowing an attacker to cause a denial of service via CPU exhaustion. The vulnerability can be exploited by supplying a malicious PKCS#12 file. Defenders should prioritize patching or mitigating this vulnerability to prevent potential denial of service attacks. Affected product context includes systems or applications using the Bouncy Castle Inc. bc-csharp library.

Defensive priority

Defenders should prioritize patching or mitigating this vulnerability to prevent potential denial of service attacks.

Recommended defensive actions

• Patch or upgrade to version 2.7.0 or later
• Restrict access to the Pkcs12Store.Load method
• Monitor for suspicious PKCS#12 file uploads or processing
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD vulnerability detail page provide information on the vulnerability, including its description, CVSS score, and affected versions. The vulnerability affects the Bouncy Castle Inc. bc-csharp library before version 2.7.0. Defenders should verify affected versions and inventory checks required. Evidence is limited to public CVE and NVD details.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.