{"id":"CVE-2026-59638","summary":"JSSE hostname verifier CN-fallback enabled by default despite documented opt-in","details":"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).","modified":"2026-10-24T14:07:50.243024447Z","published":"2026-08-03T00:57:31.904Z","related":["SUSE-SU-2026:23127-1","SUSE-SU-2026:23150-1","SUSE-SU-2026:3559-1","openSUSE-SU-2026:11445-1","openSUSE-SU-2026:21538-1"],"database_specific":{"cna_assigner":"bcorg","cwe_ids":["CWE-297"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59638.json","unresolved_ranges":[{"extracted_events":[{"source":"AFFECTED_FIELD","strategy":"StandardRange","range":[{"introduced":"1.0.7"},{"fixed":"1.0.24"},{"introduced":"2.0.0"},{"fixed":"2.0.24"},{"introduced":"2.1.0"},{"fixed":"2.1.24"}]}]}]},"references":[{"type":"WEB","url":"https://www.bouncycastle.org/download/bouncy-castle-java-fips/"},{"type":"WEB","url":"https://www.bouncycastle.org/download/bouncy-castle-java-lts/"},{"type":"WEB","url":"https://www.bouncycastle.org/download/bouncy-castle-java/"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59638.json"},{"type":"ADVISORY","url":"https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59638"},{"type":"FIX","url":"https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a"},{"type":"FIX","url":"https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b"},{"type":"PACKAGE","url":"https://github.com/bcgit/bc-java"},{"type":"PACKAGE","url":"https://github.com/bcgit/bc-lts-java"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/bcgit/bc-java","events":[{"introduced":"0f1260dc7e3c42be130c45fdad5b4363170ddf32"},{"fixed":"57fbd3c501f7a369f64eda311d6a709fc0bcae84"},{"fixed":"799bd15320a6310a447863638aa3df64acef829b"},{"fixed":"5ac55351cd1a8a7184d41c96a7ee87df0770240a"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"1.61"},{"fixed":"1.85"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"range":[{"fixed":"799bd15320a6310a447863638aa3df64acef829b"}],"source":"REFERENCES_COMMIT"},{"range":[{"fixed":"5ac55351cd1a8a7184d41c96a7ee87df0770240a"}],"source":"REFERENCES_COMMIT"}]}},{"type":"GIT","repo":"https://github.com/bcgit/bc-lts-java","events":[{"introduced":"468b5082f3f0971e80bf9edb7029c17b39b9ba0c"},{"fixed":"f101b232c5d3e07ecdd504210a57e43831d6cd65"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"2.73.0"},{"fixed":"2.73.12"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"cpe":"cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:*","range":[{"introduced":"0"},{"last_affected":"2.73.11"}],"source":"CPE_RANGE"}]}}],"versions":["r2rv73dot11","r2rv73dot10","r2rv73dot9","r2rv73dot8","r2rv73dot6","r2rv73dot4","r2rv73dot3","r2rv73dot1","r2rv73dot0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-59638.json","vanir_signatures":[{"digest":{"length":1789,"function_hash":"101243177317955593101504553558978546778"},"id":"CVE-2026-59638-0f976f65","signature_type":"Function","signature_version":"v1","source":"https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b","target":{"file":"tls/src/main/java/org/bouncycastle/jsse/provider/HostnameUtil.java","function":"checkHostname"},"deprecated":false},{"target":{"file":"tls/src/main/java/org/bouncycastle/jsse/provider/HostnameUtil.java"},"deprecated":false,"digest":{"line_hashes":["96001466807666051162215343109763009601","189586970452718852126709800966206076350","334434604823266146796290254048024465296","230984720223366777099573014615205534404"],"threshold":0.9},"id":"CVE-2026-59638-c6e56e73","signature_type":"Line","signature_version":"v1","source":"https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b"}],"vanir_signatures_modified":"2026-10-24T14:07:50Z"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V4","score":"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"}]}