{"id":"CVE-2026-103600","summary":"Unbounded ASN.1 nesting depth causes process-terminating stack overflow","details":"Uncontrolled recursion in the ASN.1 parser (Asn1InputStream, Asn1StreamParser) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote unauthenticated attacker to cause a denial of service via a crafted ASN.1 encoding of deeply nested constructed elements (for example SEQUENCE inside SEQUENCE, in definite-length DER or indefinite-length BER form), because each nesting level is parsed by a further recursive call with no bound on depth. About 2,000 levels (8 KB of DER) are enough to exhaust a 1.5 MB thread stack, the .NET main-thread default on Windows, and raise a StackOverflowException, which .NET cannot catch and which terminates the whole process; on threads with larger stacks, parse time instead grows quadratically with depth (about 9 seconds of CPU for a 64 KB input). Any path that parses untrusted ASN.1 is exposed, including X.509 certificates and CRLs, CMS/PKCS#7, PKCS#8/PKCS#12, OCSP and TLS Certificate messages.","modified":"2026-10-04T02:46:19.154765154Z","published":"2026-10-02T07:08:51.653Z","database_specific":{"cwe_ids":["CWE-674"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103600.json","cna_assigner":"bcorg"},"references":[{"type":"WEB","url":"https://www.nuget.org/packages/BouncyCastle.Cryptography"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103600.json"},{"type":"ADVISORY","url":"https://github.com/bcgit/bc-csharp/wiki/CVE-2026-103600"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-103600"},{"type":"FIX","url":"https://github.com/bcgit/bc-csharp/commit/89c81b0da7fe11cd70013285560bbc472cb73901"},{"type":"FIX","url":"https://github.com/bcgit/bc-csharp/commit/b99f4e3dcea05b57becc79dfa6ad91a54c778d65"},{"type":"PACKAGE","url":"https://github.com/bcgit/bc-csharp"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/bcgit/bc-csharp","events":[{"introduced":"0"},{"fixed":"4007498b13582d90ee1eda5d9920c324428b98b3"},{"fixed":"89c81b0da7fe11cd70013285560bbc472cb73901"},{"fixed":"b99f4e3dcea05b57becc79dfa6ad91a54c778d65"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"2.7.0"}],"source":["DESCRIPTION","REFERENCES"]}}],"versions":["release-1.9.0","release-1.8.10","release-1.8.8","release-1.8.7","release-1.8.6","release-1.8.5","release-1.8.4","release-1.8.3","release-1.8.2","release-1.8.1","release-1.8.0","release-1.8.0-RC.3","release-1.8.0-RC.2","release-1.8.0-RC.1","release-1.8.0-beta.4","release-1.8.0-beta.3","release-1.8.0-beta.2","release-1.8.0-beta.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-103600.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}