# 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. - **Severity:** Critical 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`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 3 Aug 2026 - **Updated:** 5 Oct 2026 - **Also known as:** CLEANSTART-2026-AC66923, CLEANSTART-2026-DP79525, CLEANSTART-2026-DU85767, CLEANSTART-2026-WC45215, CLEANSTART-2026-YC34424, DEBIAN-CVE-2026-8763, ECHO-e963-b6d6-07b6, GHSA-9pwp-9qqc-pr26, MINI-275g-rq85-c778, MINI-2mr3-6g2p-3vxv, MINI-3h5c-fjg2-gpvx, MINI-3q99-w4w7-x9qf, MINI-43rx-6rmx-rmf3, MINI-48x5-gvq6-cvrg, MINI-4pc9-qv9v-q8pq, MINI-538c-46qr-32xx, MINI-56g6-4q68-r7f6, MINI-5hwh-88r7-qr49, MINI-654h-6mvv-fx4v, MINI-685r-rxmp-6hmg, MINI-6gxv-v45v-p7vr, MINI-6jjj-3w88-p8mw, MINI-6v75-m42g-wf54, MINI-7pj6-2hp6-jc4r, MINI-7wr7-8fm9-rhm2, MINI-7xgv-4jr5-p845, MINI-8h9x-c4hr-qc7v, MINI-8w9g-xgpq-879w, MINI-952r-853q-98gf, MINI-98gj-6qxw-mrg6, MINI-9jx4-6x3m-wv79, MINI-9mjh-5h43-293w, MINI-9vm8-mvmq-qc78, MINI-c6m6-jj2h-83q4, MINI-cjgf-vv75-2h4j, MINI-cmg7-9rrh-rq6g, MINI-cqpg-5mg5-73xv, MINI-cqw2-m7j7-79x5, MINI-f62r-m82m-34w5, MINI-fxr2-v7xv-98x8, MINI-gg74-w4cw-wj49, MINI-gmgh-257m-vgfc, MINI-gq4c-fhmc-w6wq, MINI-gq7c-2jmx-96h2, MINI-gw5p-h7jv-873p, MINI-h57v-vr5f-4ffp, MINI-hhpw-cxwh-6hrw, MINI-hjf5-v3r6-5qx7, MINI-hmr9-c2mj-fg33, MINI-hpr6-xqhq-c9v2, MINI-hvrj-3c9g-mvxr, MINI-hxgm-fhpg-2px6, MINI-j8vj-jv47-g323, MINI-jf84-387v-wqh3, MINI-mhx4-rhv9-h74x, MINI-mpcq-jqpj-6f44, MINI-p426-q6x4-grgv, MINI-phmq-vj89-qxx5, MINI-qjcq-f9x5-xrjw, MINI-rg24-f792-24vc, MINI-v3cp-whgx-rr2j, MINI-vjcv-wx4h-cgrc, MINI-vjvp-g2gv-8qhr, MINI-vppm-m4m2-wpr5, MINI-w4qp-wm7g-8h36, MINI-wfhp-7cm4-r784, MINI-wh8f-f4f5-hm9m, MINI-wrrc-jp68-6354, MINI-x4jw-3qxm-646q, MINI-x8hj-rvwc-52mm, MINI-xc4w-f29r-6gvv, MINI-xrm3-3h89-hmjx, ROOT-APP-MAVEN-CVE-2026-8763, UBUNTU-CVE-2026-8763 ## 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 (Improper Certificate Validation) ## 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 | Ecosystem | 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 | | `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: 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](https://insights.sbomify.com/CVE-2007-6721/): Legion of the Bouncy Castle Java Cryptography API Bleichenbacher Oracle Vulnerability (critical 10.0) - [CVE-2018-1000613](https://insights.sbomify.com/CVE-2018-1000613/): Deserialization of Untrusted Data in Bouncy castle (critical 9.8) - [CVE-2026-58062](https://insights.sbomify.com/CVE-2026-58062/): Stapled OCSP response accepted without binding to the checked certificate (critical 9.3) - [CVE-2026-59638](https://insights.sbomify.com/CVE-2026-59638/): JSSE hostname verifier CN-fallback enabled by default despite documented opt-in (critical 9.3) - [CVE-2026-59650](https://insights.sbomify.com/CVE-2026-59650/): MTI/A0 DH agreement exponentiates unvalidated peer value (critical 9.3) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-8763 and fix it if it is affected. What it is: 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. Exploitation: There is no known exploitation of CVE-2026-8763 in the wild and no public exploit code. Affected packages and fixed versions: - org.bouncycastle:bc-fips (Maven): affected all versions; fixed in 1.0.2.7 - org.bouncycastle:bc-fips (Maven): affected all versions; fixed in 1.0.2.7 - org.bouncycastle:bc-fips (Maven): affected from 2.0.0; fixed in 2.0.2 - org.bouncycastle:bc-fips (Maven): affected from 2.0.0; fixed in 2.0.2 - org.bouncycastle:bc-fips (Maven): affected from 2.1.0; fixed in 2.1.3 - org.bouncycastle:bc-fips (Maven): affected from 2.1.0; fixed in 2.1.3 - org.bouncycastle:bcprov-jdk15to18 (Maven): affected all versions; fixed in 1.85 - org.bouncycastle:bcprov-jdk15to18 (Maven): affected all versions; fixed in 1.85 - org.bouncycastle:bcprov-jdk18on (Maven): affected all versions; fixed in 1.85 - org.bouncycastle:bcprov-jdk18on (Maven): affected all versions; fixed in 1.85 - org.bouncycastle:bcprov-lts8on (Maven): affected all versions; fixed in 2.73.12 - org.bouncycastle:bcprov-lts8on (Maven): affected all versions; fixed in 2.73.12 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-8763/ (Markdown: https://insights.sbomify.com/CVE-2026-8763/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8763 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8763 - OSV: https://osv.dev/vulnerability/CVE-2026-8763 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-8763/ Summaries are generated and may contain mistakes; the official description above is the record.