CVE-2026-103600: Legion of the · Uncontrolled Recursion
Source GCVE Database
Not known to be exploited · CVSS 8.7 High : upgrade to 2.7.0 soon.
Data as of 28 Oct 2026, 17:11 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.7.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 2 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade bc-csharp and BouncyCastle.Cryptography to 2.7.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Legion of the Bouncy Castle Inc.bc-csharp | Affected
| Fixed in
|
NuGetBouncyCastle.Cryptographypkg:nuget/BouncyCastle.CryptographyOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Users should upgrade to Bouncy Castle bc-csharp version 2.7.0 or later, where this issue is fixed. Avoid parsing untrusted ASN.1 data with vulnerable versions until patched.
Description
A vulnerability in the ASN.1 parser components (Asn1InputStream, Asn1StreamParser) of the Bouncy Castle bc-csharp library before version 2.7.0 allows remote unauthenticated attackers to cause a denial of service. This occurs due to uncontrolled recursion when parsing deeply nested ASN.1 constructed elements, leading to stack exhaustion and process termination. The flaw affects parsing of various ASN.1-based data such as X.509 certificates, CRLs, CMS/PKCS#7, PKCS#8/PKCS#12, OCSP, and TLS certificate messages.
References
- nvd.nist.gov/vuln/detail/CVE-2026-103600 (opens in a new tab)
- github.com/bcgit/bc-csharp/commit/89c81b0da7fe11cd70013285560bbc472cb73901 (opens in a new tab)
- github.com/bcgit/bc-csharp/commit/b99f4e3dcea05b57becc79dfa6ad91a54c778d65 (opens in a new tab)
- github.com/bcgit/bc-csharp/wiki/CVE-2026-103600 (opens in a new tab)