Security Digest · Vulnerability record
CVE-2026-8763: Bouncy Castle: Name Constraints bypass via trailing dot in rfc822Name and URI
In Bouncy Castle for Java before 1.85, Name Constraints bypass via trailing dot in rfc822Name and URI.
CVSS 9.3 Critical EPSS 0.4% · p36
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- 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).
From the GitHub advisory
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).
Weakness type: CWE-295.
Product: org.bouncycastle:bc-fips (Maven) · Assigned by: bcorg · Published: 2026-08-03
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Maven | org.bouncycastle:bc-fips | < 1.0.2.7 | 1.0.2.7 |
| Maven | org.bouncycastle:bc-fips | >= 2.0.0, < 2.0.2 | 2.0.2 |
| Maven | org.bouncycastle:bc-fips | >= 2.1.0, < 2.1.3 | 2.1.3 |
| Maven | org.bouncycastle:bcprov-jdk18on | < 1.85 | 1.85 |
| Maven | org.bouncycastle:bcprov-lts8on | < 2.73.12 | 2.73.12 |
| Maven | org.bouncycastle:bcprov-jdk15to18 | < 1.85 | 1.85 |
| Vendor | Product | Affected versions (per 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 scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| bcorg | 4.0 | 9.3 Critical | 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 | 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 |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: none (no login)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- 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.
Timeline
- — CVE record published by bcorg
- — GitHub-reviewed advisory GHSA-9pwp-9qqc-pr26 published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- github.com github.com
- github.com github.com
Vulnerability records
- GitHub Advisory GHSA-9pwp-9qqc-pr26 github.com
- CVE.org record CVE-2026-8763 cve.org
- NVD entry CVE-2026-8763 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com