# CVE-2026-103600: Bouncy Castle ASN.1 parser uncontrolled recursion

Source: https://junglewise.ai/threats/cve-2026-103600-uncontrolled-recursion-in-the-asn-1-parser-asn1inputstream  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-02. Updated: 2026-10-05  
License: CC BY 4.0 with a link back

CVE-2026-103600 · Severity: info · Published 2026-10-02

Bouncy Castle is a cryptography library used to parse certificates, encryption protocols, and other security-critical data formats. A vulnerability in its ASN.1 parser allows an attacker to send specially crafted nested data structures that cause the application to crash with a stack overflow, resulting in denial of service. This affects any application using the library to parse untrusted certificates or encrypted messages.

Technologies: [Legion of the Bouncy Castle Inc. BouncyCastle.Cryptography](https://junglewise.ai/threats/technologies/legion-of-the-bouncy-castle-inc-bouncycastle-cryptography). Vendors: [Legion of the Bouncy Castle Inc.](https://junglewise.ai/threats/vendors/legion-of-the-bouncy-castle-inc).

## Quick answers

**Is CVE-2026-103600 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103600 being exploited in the wild.

**How severe is CVE-2026-103600?** Informational severity, published 2 October 2026.

**Which products and versions are affected?** Legion of the Bouncy Castle Inc. BouncyCastle.Cryptography before 2.7.0.

**Is there a fix for CVE-2026-103600?** Yes: fixed in 2.7.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-103600 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-103600?** Check whether you run Legion of the Bouncy Castle Inc. BouncyCastle.Cryptography at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 2.7.0

## Technical details

The Asn1InputStream and Asn1StreamParser classes in Bouncy Castle recursively parse constructed ASN.1 elements without enforcing a depth limit, allowing an attacker to craft deeply nested structures (approximately 2,000 levels in 8 KB) that exhaust the thread stack and raise an uncatchable StackOverflowException. The vulnerability affects all code paths that parse untrusted ASN.1 data, including X.509 certificates, CRLs, CMS/PKCS#7, PKCS#8/PKCS#12, OCSP, and TLS Certificate messages; the fix introduces a configurable MaxDepth property with a default limit of 32.

## Affected products

- Legion of the Bouncy Castle Inc. BouncyCastle.Cryptography before 2.7.0

## Timeline

- 2026-10-02: disclosed

## References

- [https://www.nuget.org/packages/BouncyCastle.Cryptography](https://www.nuget.org/packages/BouncyCastle.Cryptography)
- [https://github.com/bcgit/bc-csharp/commit/89c81b0da7fe11cd70013285560bbc472cb73901](https://github.com/bcgit/bc-csharp/commit/89c81b0da7fe11cd70013285560bbc472cb73901)

## Related threats

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- [Bouncy Castle CCM AEAD decryption plaintext disclosure](https://junglewise.ai/threats/cve-2026-103601-release-of-unverified-plaintext-in-the-ccm-ccmblockcipher-and)
- [Bouncy Castle C# DHAgreement improper input validation](https://junglewise.ai/threats/cve-2026-63569-improper-input-validation-in-dhagreement-calculateagreement-mti)
- [Bouncy Castle C# IesEngine padding oracle in CBC mode](https://junglewise.ai/threats/cve-2026-63567-observable-discrepancy-in-iesengine-decryptblock-in-legion-of-the)