CVE-2026-103602 json
Name constraints bypass via trailing dot in rfc822Name, dNSName and URI hosts
published last mo. modified 12d ago also EUVD-2026-91232
- cvss
- 5.3
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 14%
- public exploits
- 0
- none known
Summary
Improper certificate validation in PkixNameConstraintValidator in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can obtain certificates from, a name-constrained intermediate CA to have certificates accepted during PKIX certification path validation for email addresses, DNS names or URI hosts that lie within excluded subtrees applying to that CA, via an rfc822Name, dNSName or uniformResourceIdentifier name whose host ends with a dot, because names and constraints were compared without first removing the RFC 1034 root-label trailing dot, so a fully qualified host name did not match an excluded subtree for the same host written without the dot.
Patch / fix
- Legion of the Bouncy Castle Inc. bc-csharp 2.7.0
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- last mo.
Exploit prediction
0.23% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.2 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N |
| CNA | 4.0 | 8.2 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/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:X |
| NVD | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
Affected products
- Legion of the Bouncy Castle Inc. bc-csharp
Classification
- Weakness
-
- CWE-295 Improper Certificate Validation
References
-
github.com
/bcgit/bc-csharp/commit/f196a22bbf7765cc19b0c4f4645c74ea7ad35e09
patch
-
github.com
/bcgit/bc-csharp/commit/be276e057775a6a674a62e9d9a2583b229978f73
patch
-
github.com
/bcgit/bc-csharp/commit/75c3c576602886180ed92a63c89419e3bd63b392
patch
-
github.com
/bcgit/bc-csharp/wiki/CVE-2026-103602
vendor-advisory, patch
Sources
- CVE List CVE-2026-103602
- NVD CVE-2026-103602
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