CVE-2026-8763 Name Constraints bypass via trailing dot in rfc822Name and URI
Attackers can bypass X.509 Name Constraints in Bouncy Castle Java libraries by using trailing dots in email or URI fields, undermining certificate validation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-8763?
CVE-2026-8763 is a critical vulnerability in Bouncycastle Bc-Java, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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: CWE-295
Which versions are affected by CVE-2026-8763?
12 open source packages ship an affected version, including org.bouncycastle:bc-fips, org.bouncycastle:bcprov-jdk15to18 and org.bouncycastle:bcprov-jdk18on. It affects 3 products.
| Package | Affected | Fixed in |
|---|---|---|
org.bouncycastle:bc-fips Maven | All versions | 1.0.2.7 |
org.bouncycastle:bc-fips Maven | All versions | 1.0.2.7 |
org.bouncycastle:bc-fips Maven | From 2.0.0 | 2.0.2 |
org.bouncycastle:bc-fips Maven | From 2.0.0 | 2.0.2 |
org.bouncycastle:bc-fips Maven | From 2.1.0 | 2.1.3 |
org.bouncycastle:bc-fips Maven | From 2.1.0 | 2.1.3 |
6 more packages
org.bouncycastle:bcprov-jdk15to18 Maven | All versions | 1.85 |
org.bouncycastle:bcprov-jdk15to18 Maven | All versions | 1.85 |
org.bouncycastle:bcprov-jdk18on Maven | All versions | 1.85 |
org.bouncycastle:bcprov-jdk18on Maven | All versions | 1.85 |
org.bouncycastle:bcprov-lts8on Maven | All versions | 2.73.12 |
org.bouncycastle:bcprov-lts8on Maven | All versions | 2.73.12 |
Products include Bouncycastle Bc-Java, Bouncycastle Bouncy Castle for Java Lts, Bouncycastle Fips Java Api.
How do I fix CVE-2026-8763?
Upgrade org.bouncycastle:bc-fips to a fixed version for your release line: 1.0.2.7, 2.0.2 or 2.1.3.
Is CVE-2026-8763 being exploited?
There is no known exploitation of CVE-2026-8763 in the wild and no public exploit code.
Other vulnerabilities in Bouncycastle Bc-Java
- CVE-2007-6721 Legion of the Bouncy Castle Java Cryptography API Bleichenbacher Oracle Vulnerability
- CVE-2018-1000613 Deserialization of Untrusted Data in Bouncy castle
- CVE-2026-58062 Stapled OCSP response accepted without binding to the checked certificate
- CVE-2026-59638 JSSE hostname verifier CN-fallback enabled by default despite documented opt-in
- CVE-2026-59650 MTI/A0 DH agreement exponentiates unvalidated peer value
Sources
Also known as CLEANSTART-2026-AC66923, CLEANSTART-2026-DP79525, CLEANSTART-2026-DU85767, CLEANSTART-2026-WC45215, CLEANSTART-2026-YC34424, DEBIAN-CVE-2026-8763 and 68 more.