CVE-2026-103602

8.2 HIGH 0.2% exploit odds Fix listed Crypto

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data tampering.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-09-30 23:01 UTC ReservedThe CVE id was reserved by its CNA
2026-10-02 08:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-28 13:30 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 8.2 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-10-02 08:17 UTC
Last modified: 2026-10-28 13:30 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-295 · Improper certificate validation
Record status: Analyzed

Affected

Bouncycastle bc-csharp < 2.7.0

Attack profile CVSS 4.0 · 8.2

Attack vector: Network
Complexity: Low
Attack requirements: Present
Privileges needed: None
User interaction: None
Confidentiality: None
Integrity: High
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-103602.md and follow it. Check whether this project is affected by CVE-2026-103602. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

· More options · Status badge

Download Square Reddit

Fix and advisories

References

NVD record · CVE.org record