{"answers":{"affected":"It affects 3 products.","exploited":"There is no known exploitation of CVE-2026-59638 in the wild and no public exploit code.","fix":"Upgrade to a fixed version.","what":"CVE-2026-59638 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."},"fix_prompt":"Check this codebase for CVE-2026-59638 and fix it if it is affected.\n\nWhat it is: CVE-2026-59638 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.\nExploitation: There is no known exploitation of CVE-2026-59638 in the wild and no public exploit code.\n\nAffected product: Bouncycastle Bc-Java. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. 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.\n2. 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.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-59638/ (Markdown: https://insights.sbomify.com/CVE-2026-59638/index.md)","id":"CVE-2026-59638","markdown":"https://insights.sbomify.com/CVE-2026-59638/index.md","name":"CVE-2026-59638","record":{"aliases":["CLEANSTART-2026-OW17581","DEBIAN-CVE-2026-59638","GHSA-8rxj-3p7p-rq39","UBUNTU-CVE-2026-59638"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"Java cryptography library","requires_auth":"none","summary":"Bouncy Castle for Java enables hostname verifier CN-fallback by default, bypassing intended security controls and allowing potential man-in-the-middle attacks.","user_interaction":"not_required","vuln_class":"security_feature_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"bcorg","cpe":[{"product":"bc-java","vendor":"bouncycastle"},{"product":"bctls-fips","vendor":"bouncycastle"},{"product":"bouncy_castle_for_java_lts","vendor":"bouncycastle"}],"cvss":{"score":9.3,"severity":"critical","source":"cna","vector":"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","version":"4.0"},"cwes":[{"id":"CWE-297","name":"Improper Validation of Certificate with Host Mismatch"}],"description":"In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"JSSE hostname verifier CN-fallback enabled by default despite documented opt-in","id":"CVE-2026-59638","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"bouncycastle:bc-java","products":["bouncycastle:bc-java"],"type":"security_feature_bypass","year":"2026"},"n_packages":0,"n_references":3,"next":{"headline":"CMS verifySignatures returns true for SignedData with zero signers","id":"CVE-2026-59639"},"packages":[],"prev":{"headline":"Android ZCC denial of service","id":"CVE-2026-59570"},"products":["BC-FJA","BC-JAVA","BC-LTS-JAVA"],"published":"2026-08-03","related":[{"cvss_score":10,"headline":"Legion of the Bouncy Castle Java Cryptography API Bleichenbacher Oracle Vulnerability","id":"CVE-2007-6721","kev_date_added":null,"published":"2009-03-30"},{"cvss_score":9.8,"headline":"Deserialization of Untrusted Data in Bouncy castle","id":"CVE-2018-1000613","kev_date_added":null,"published":"2018-07-09"},{"cvss_score":9.3,"headline":"Stapled OCSP response accepted without binding to the checked certificate","id":"CVE-2026-58062","kev_date_added":null,"published":"2026-08-03"},{"cvss_score":9.3,"headline":"MTI/A0 DH agreement exponentiates unvalidated peer value","id":"CVE-2026-59650","kev_date_added":null,"published":"2026-08-03"},{"cvss_score":9.3,"headline":"Name Constraints bypass via trailing dot in rfc822Name and URI","id":"CVE-2026-8763","kev_date_added":null,"published":"2026-08-03"},{"cvss_score":8.7,"headline":"MLS membership checks compare a uint32 leaf_index as signed, admitting an out-of-range sender","id":"CVE-2026-17507","kev_date_added":null,"published":"2026-10-02"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"yes","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-08-03","vendors":["Legion of the Bouncy Castle Inc."]},"summary":"Bouncy Castle for Java enables hostname verifier CN-fallback by default, bypassing intended security controls and allowing potential man-in-the-middle attacks.","url":"https://insights.sbomify.com/CVE-2026-59638/"}