Review reviewHigh

CVE-2026-13506

Legion of the Bouncy Castle Inc. BC-JAVA, BC-LTS-JAVA, BC-FJA

In Bouncy Castle for Java before 1.85, Lazy ASN.1 sequence forcing resets nesting-depth guard. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bc-fips 1.0.2.7 (1.0.X series), 2.0.2 (2.0.X series) and 2.1.3 (2.1.X series).

CVSS: 8.7
EPSS: 0.26%
CISA KEV: Not listed
Published: 2026.08.03

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.26%

Technical severityCVSS 8.7

Vulnerability overview

Affected product and versions

Product: Legion of the Bouncy Castle Inc. BC-JAVA, BC-LTS-JAVA, BC-FJA
Affected versions: < 1.85, >= 2.73.0 < 2.73.12, >= 1.0.0 < 1.0.2.7, >= 2.0.0 < 2.0.2, >= 2.1.0 < 2.1.3
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that Legion of the Bouncy Castle Inc. BC-JAVA, BC-LTS-JAVA, BC-FJA and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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
CWE: CWE-674