CVE-2026-13506

Bouncy Castle: Lazy ASN.1 sequence forcing resets nesting-depth guard

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).

CVE-2026-13506 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.85, 1.0.2.7, 2.0.2, 2.1.3, 2.73.12); upgrading removes the vulnerable code path.

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1. What is CVE-2026-13506? CVE-2026-13506 is a high-severity security vulnerability in org.bouncycastle:bcprov-jdk18on (maven), affecting versions < 1.85. It is fixed in 1.85, 1.0.2.7, 2.0.2, 2.1.3, 2.73.12.
2. How severe is CVE-2026-13506? CVE-2026-13506 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-13506?
   • org.bouncycastle:bcprov-jdk18on (maven) (versions < 1.85)
   • org.bouncycastle:bc-fips (maven) (versions < 1.0.2.7)
   • org.bouncycastle:bcprov-lts8on (maven) (versions < 2.73.12)
   • org.bouncycastle:bcprov-jdk15to18 (maven) (versions < 1.85)
4. Is there a fix for CVE-2026-13506? Yes. CVE-2026-13506 is fixed in 1.85, 1.0.2.7, 2.0.2, 2.1.3, 2.73.12. Upgrade to this version or later.
5. Is CVE-2026-13506 exploitable, and should I be worried? Whether CVE-2026-13506 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-13506 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-13506?
   • Upgrade org.bouncycastle:bcprov-jdk18on to 1.85 or later
   • Upgrade org.bouncycastle:bc-fips to 1.0.2.7 or later
   • Upgrade org.bouncycastle:bc-fips to 2.0.2 or later
   • Upgrade org.bouncycastle:bc-fips to 2.1.3 or later
   • Upgrade org.bouncycastle:bcprov-lts8on to 2.73.12 or later
   • Upgrade org.bouncycastle:bcprov-jdk15to18 to 1.85 or later

Other vulnerabilities in org.bouncycastle:bcprov-jdk18on