---
title: "CVE-2026-8763: Bouncy Castle: Name Constraints bypass via trailing dot in rfc822Name and URI"
url: https://erroneo.us/security/cve/CVE-2026-8763/
description: "CVE-2026-8763 (org.bouncycastle:bc-fips (Maven)): In Bouncy Castle for Java before 1.85, Name Constraints bypass via trailing dot in rfc822Name and URI.…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-08-03
date_modified: 2026-10-05
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-8763"
kev: false
cvss: 9.3
epss: 0.0043
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-8763: Bouncy Castle: Name Constraints bypass via trailing dot in rfc822Name and URI

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.4% , percentile 36: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 36% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes org.bouncycastle:bc-fips (Maven) < 1.0.2.7, fixed in 1.0.2.7 ; org.bouncycastle:bc-fips (Maven) >= 2.0.0, < 2.0.2, fixed in 2.0.2 ; org.bouncycastle:bc-fips (Maven) >= 2.1.0, < 2.1.3, fixed in 2.1.3 ; org.bouncycastle:bcprov-jdk18on (Maven) < 1.85, fixed in 1.85 . Check your lockfile, including transitive dependencies.

## What it is

In Bouncy Castle for Java before 1.85, Name Constraints bypass via trailing dot in rfc822Name and URI. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bc-fips 1.0.2.7 (1.0.X series), 2.0.2 (2.0.X series) and 2.1.3 (2.1.X series).

## Affected packages

- Maven `org.bouncycastle:bc-fips` < 1.0.2.7 → fixed: 1.0.2.7
- Maven `org.bouncycastle:bc-fips` >= 2.0.0, < 2.0.2 → fixed: 2.0.2
- Maven `org.bouncycastle:bc-fips` >= 2.1.0, < 2.1.3 → fixed: 2.1.3
- Maven `org.bouncycastle:bcprov-jdk18on` < 1.85 → fixed: 1.85
- Maven `org.bouncycastle:bcprov-lts8on` < 2.73.12 → fixed: 2.73.12
- Maven `org.bouncycastle:bcprov-jdk15to18` < 1.85 → fixed: 1.85

## Affected products (CVE record)

- Legion of the Bouncy Castle Inc. BC-JAVA: < 1.85
- Legion of the Bouncy Castle Inc. BC-LTS-JAVA: 2.73.0 < 2.73.12
- Legion of the Bouncy Castle Inc. BC-FJA: 1.0.0 < 1.0.2.7, 2.0.0 < 2.0.2, 2.1.0 < 2.1.3

## Severity

- bcorg CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber`
- GitHub CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.43% probability of exploitation activity in the next 30 days; percentile 36.

## Sources

- [github.com](https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%908763)
- [github.com](https://github.com/bcgit/bc-java/commit/2c28b253a44681fbbc562561eab6ad383d2ae558)
- [GitHub Advisory GHSA-9pwp-9qqc-pr26](https://github.com/advisories/GHSA-9pwp-9qqc-pr26)
- [CVE.org record CVE-2026-8763](https://www.cve.org/CVERecord?id=CVE-2026-8763)
- [NVD entry CVE-2026-8763](https://nvd.nist.gov/vuln/detail/CVE-2026-8763)
- [github.com](https://github.com/bcgit/bc-java/wiki/CVE-2026-8763)
- [github.com](https://github.com/bcgit/bc-java/releases/tag/r1rv85v2)

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Source page: https://erroneo.us/security/cve/CVE-2026-8763/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt