Is CVE-2026-8763 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-8763 being exploited in the wild.

How severe is CVE-2026-8763?

Critical severity, with a CVSS score of 9.1, published 3 August 2026.

Which products and versions are affected?

Bouncy Castle Bcprov-Jdk15to18 before 1.85; Bouncy Castle Bcprov-Jdk18on before 1.85; Bouncy Castle Bcprov-Lts8on before 2.73.12; org.bouncycastle:bc-fips (Maven) ECOSYSTEM:introduced=0,fixed=1.0.2.7; and 3 more.

Is there a fix for CVE-2026-8763?

Yes. org.bouncycastle:bc-fips (Maven): upgrade to 1.0.2.7 or later; org.bouncycastle:bcprov-jdk15to18 (Maven): upgrade to 1.85 or later; org.bouncycastle:bcprov-jdk18on (Maven): upgrade to 1.85 or later; org.bouncycastle:bcprov-lts8on (Maven): upgrade to 2.73.12 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-8763 attacked?

It is attacked over the network.

Am I affected by CVE-2026-8763?

Check whether you run Bouncy Castle Bcprov-Jdk15to18, Bouncy Castle Bcprov-Jdk18on, Bouncy Castle Bcprov-Lts8on or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

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

CVE-2026-8763 · Severity: critical · CVSS 9.1 · Published 2026-08-03

Bouncy Castle is a cryptography library used by Java applications to handle certificate validation and X.509 certificate chain processing. A flaw in the Name Constraints validation logic allows attackers to bypass certificate name verification by appending a trailing dot to domain names in email addresses and URIs. This could enable attackers to issue fraudulent certificates that pass validation checks, potentially leading to man-in-the-middle attacks, credential theft, and compromise of encrypted communications.

Technologies: org.bouncycastle:bc-fips (Maven), org.bouncycastle:bcprov-jdk15to18 (Maven), org.bouncycastle:bcprov-jdk18on (Maven), org.bouncycastle:bcprov-lts8on (Maven). Vendors: Bouncy Castle, Maven.

Quick answers

Is CVE-2026-8763 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-8763 being exploited in the wild.
How severe is CVE-2026-8763?: Critical severity, with a CVSS score of 9.1, published 3 August 2026.
Which products and versions are affected?: Bouncy Castle Bcprov-Jdk15to18 before 1.85; Bouncy Castle Bcprov-Jdk18on before 1.85; Bouncy Castle Bcprov-Lts8on before 2.73.12; org.bouncycastle:bc-fips (Maven) ECOSYSTEM:introduced=0,fixed=1.0.2.7; and 3 more.
Is there a fix for CVE-2026-8763?: Yes. org.bouncycastle:bc-fips (Maven): upgrade to 1.0.2.7 or later; org.bouncycastle:bcprov-jdk15to18 (Maven): upgrade to 1.85 or later; org.bouncycastle:bcprov-jdk18on (Maven): upgrade to 1.85 or later; org.bouncycastle:bcprov-lts8on (Maven): upgrade to 2.73.12 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-8763 attacked?: It is attacked over the network.
Am I affected by CVE-2026-8763?: Check whether you run Bouncy Castle Bcprov-Jdk15to18, Bouncy Castle Bcprov-Jdk18on, Bouncy Castle Bcprov-Lts8on or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

org.bouncycastle:bc-fips (Maven): upgrade to 1.0.2.7 or later

# set org.bouncycastle:bc-fips to 1.0.2.7 in your pom.xml or build.gradle

org.bouncycastle:bcprov-jdk15to18 (Maven): upgrade to 1.85 or later

# set org.bouncycastle:bcprov-jdk15to18 to 1.85 in your pom.xml or build.gradle

org.bouncycastle:bcprov-jdk18on (Maven): upgrade to 1.85 or later

# set org.bouncycastle:bcprov-jdk18on to 1.85 in your pom.xml or build.gradle

org.bouncycastle:bcprov-lts8on (Maven): upgrade to 2.73.12 or later

# set org.bouncycastle:bcprov-lts8on to 2.73.12 in your pom.xml or build.gradle

Technical details

The vulnerability is an improper certificate validation flaw (CWE-295) in Bouncy Castle's Name Constraints checking for rfc822Name and URI fields. The root cause is insufficient validation that allows trailing dots in domain names to bypass Name Constraints restrictions. An attacker can craft a certificate with a rfc822Name or URI containing a trailing dot (e.g., "attacker.com.") that will bypass name constraints intended to restrict issuance to specific domains. The attack requires network reachability to a system using Bouncy Castle for certificate validation, requires no authentication or user interaction, and can be exploited remotely. Patches are available: version 1.85 for bcprov-jdk15to18/jdk18on, version 2.73.12 for bcprov-lts8on, and version 1.0.2.7/2.0.2/2.1.3 for bc-fips across its version branches.

Affected products

Bouncy Castle bcprov-jdk15to18 before 1.85
Bouncy Castle bcprov-jdk18on before 1.85
Bouncy Castle bcprov-lts8on before 2.73.12
Bouncy Castle bc-fips before 1.0.2.7 (1.0.X), before 2.0.2 (2.0.X), before 2.1.3 (2.1.X)

Identifiers

CVE-2026-8763
GHSA-9pwp-9qqc-pr26

Timeline

2026-08-03: disclosed
2026-08-03: patched: Patches released: bcprov 1.85, bcprov-lts8on 2.73.12, bc-fips 1.0.2.7/2.0.2/2.1.3

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