{"id":"CVE-2026-25834","aliases":["ALPINE-CVE-2026-25834","DEBIAN-CVE-2026-25834","EUVD-2026-17967","GHSA-8j6f-944f-8jmj","SUSE-SU-2026:1952-1","SUSE-SU-2026:21440-1","SUSE-SU-2026:21981-1","SUSE-SU-2026:22016-1","UBUNTU-CVE-2026-25834","openSUSE-SU-2026:10498-1","openSUSE-SU-2026:20875-1","openSUSE-SU-2026:21144-1"],"status":"published","title":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"adp","from":"cve"},"epss":{"day":"2026-11-10","score":0.00141,"percentile":0.03448,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-295","CWE-327"],"published":"2026-04-01T00:00:00Z","modified":"2026-11-03T06:33:01Z","fixes":[{"ecosystem":"Alpine:v3.20","package":"mbedtls","fixed_in":["3.6.6-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.21","package":"mbedtls","fixed_in":["3.6.6-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.22","package":"mbedtls","fixed_in":["3.6.6-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.23","package":"mbedtls","fixed_in":["3.6.6-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.24","package":"mbedtls","fixed_in":["3.6.6-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.24","package":"mbedtls3","fixed_in":["3.6.6-r0"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"mbedtls","fixed_in":["3.6.6-0.1~deb13u1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"mbedtls","fixed_in":["3.6.6-0.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Alpine:v3.20","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.21","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.22","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.23","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"mbedtls3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-r0"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-0.1~deb13u1"}]}],"versions":["3.6.4-2","3.6.5-0.1","3.6.5-0.1~deb13u1"]},{"source":"osv","ecosystem":"Debian:14","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-0.1"}]}],"versions":["3.6.4-2","3.6.5-0.1","3.6.5-0.1~deb13u1","3.6.6-0.1~deb13u1"]},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 16.0","package":"ovmf","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"202502-160000.5.1"}]}],"bundled":4},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP applications 16.0","package":"ovmf","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"202502-160000.5.1"}]}],"bundled":4},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.2-1","2.2.0-1","2.2.1-1","2.2.1-2","2.2.1-2ubuntu0.1","2.2.1-2ubuntu0.2","2.2.1-2ubuntu0.3"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.5.1-1ubuntu1","2.6.0-1","2.7.0-2","2.8.0-1","2.8.0-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.16.2-1","2.16.3-1","2.16.4-1ubuntu2","2.16.4-1ubuntu2+esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.16.9-0.1ubuntu1","2.16.11-0.1ubuntu1","2.16.11-0.3","2.28.0-1","2.28.0-1build1","2.28.0-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.28.3-1","2.28.6-1ubuntu1","2.28.7-1ubuntu1","2.28.7-1.1ubuntu1","2.28.8-1","2.28.8-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.6.2-3ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.6.5-0.1ubuntu2","3.6.6-0.1ubuntu1","3.6.7-3ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.6.2-3ubuntu1","3.6.5-0.1ubuntu1","3.6.5-0.1ubuntu2"]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-1.1"}]}],"bundled":10},{"source":"osv","ecosystem":"openSUSE:Leap 16.0","package":"mbedtls","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.6-bp160.1.1"}]}],"bundled":15}],"products":[{"vendor":"trustedfirmware","product":"mbed_tls"}],"references":[{"url":"https://mbed-tls.readthedocs.io/en/latest/security-advisories/","tags":["Vendor Advisory","advisory"]},{"url":"https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-sigalg-injection/","tags":["Vendor Advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25834","tags":["advisory"]},{"url":"https://mbed-tls.readthedocs.io/en/latest/security-advisories"},{"url":"https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-sigalg-injection"},{"url":"https://github.com/advisories/GHSA-8j6f-944f-8jmj"},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-25834","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25834.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-25834","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-20261952-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1261469","tags":["report"]},{"url":"https://bugzilla.suse.com/1261476","tags":["report"]},{"url":"https://bugzilla.suse.com/1261477","tags":["report"]},{"url":"https://bugzilla.suse.com/1261478","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2026-25833","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-25834","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-25835","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34874","tags":["web"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202621440-1/","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202621981-1/","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202622016-1/","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-25834","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-25834","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34871","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34872","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34873","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34875","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34876","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34877","tags":["web"]},{"url":"https://bugzilla.suse.com/1231708","tags":["report"]},{"url":"https://bugzilla.suse.com/1240051","tags":["report"]},{"url":"https://bugzilla.suse.com/1240052","tags":["report"]},{"url":"https://bugzilla.suse.com/1245808","tags":["report"]},{"url":"https://bugzilla.suse.com/1245809","tags":["report"]},{"url":"https://bugzilla.suse.com/1245810","tags":["report"]},{"url":"https://bugzilla.suse.com/1245811","tags":["report"]},{"url":"https://bugzilla.suse.com/1246783","tags":["report"]},{"url":"https://bugzilla.suse.com/1246784","tags":["report"]},{"url":"https://bugzilla.suse.com/1246973","tags":["report"]},{"url":"https://bugzilla.suse.com/1252341","tags":["report"]},{"url":"https://bugzilla.suse.com/1252454","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2024-49195","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-27809","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-27810","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-47917","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-48965","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-49087","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-49600","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-49601","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-52496","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-52497","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-54764","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-59438","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-25834","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","status":"published","published":"2026-04-01T00:00:00Z","modified":"2026-04-01T18:54:32.185Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"adp"}],"cwes":["CWE-295","CWE-327"],"updated_at":"2026-11-02T13:41:19.694734Z"}],"euvd":[{"id":"EUVD-2026-17967","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","status":"published","published":"2026-04-01T00:00:00Z","modified":"2026-04-01T18:54:32Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"updated_at":"2026-11-02T19:25:24.09733Z"}],"ghsa":[{"id":"GHSA-8j6f-944f-8jmj","title":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","status":"published","published":"2026-04-01T18:36:38Z","modified":"2026-04-01T21:30:30Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"cwes":["CWE-295"],"updated_at":"2026-11-02T15:07:04.885246Z"}],"nvd":[{"id":"CVE-2026-25834","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","status":"published","published":"2026-04-01T18:16:28.127Z","modified":"2026-06-17T10:25:18.51Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium","assessor":"secondary"}],"cwes":["CWE-295","CWE-327"],"updated_at":"2026-11-02T14:12:12.73929Z"}],"osv":[{"id":"ALPINE-CVE-2026-25834","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","status":"published","published":"2026-04-01T18:16:28.127Z","modified":"2026-11-03T06:33:01.951968417Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"updated_at":"2026-11-03T07:15:53.944853Z"},{"id":"CVE-2026-25834","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","status":"published","published":"2026-04-01T00:00:00Z","modified":"2026-10-28T02:30:34.37406835Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"updated_at":"2026-11-02T15:44:59.80315Z"},{"id":"DEBIAN-CVE-2026-25834","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","status":"published","published":"2026-04-01T18:16:28.127Z","modified":"2026-10-01T03:03:00.95482359Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"updated_at":"2026-11-02T15:45:53.877573Z"},{"id":"UBUNTU-CVE-2026-25834","description":"Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.","status":"published","published":"2026-04-01T18:16:00Z","modified":"2026-10-17T12:56:17.997114184Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","level":"medium"}],"updated_at":"2026-11-02T16:56:08.726452Z"},{"id":"openSUSE-SU-2026:10498-1","title":"libeverest-3.6.6-1.1 on GA media","description":"These are all security issues fixed in the libeverest-3.6.6-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-04-07T00:00:00Z","modified":"2026-04-08T07:50:16.855666Z","updated_at":"2026-11-02T16:58:38.415593Z"},{"id":"openSUSE-SU-2026:20875-1","title":"Security update for ovmf","description":"This update for ovmf fixes the following issues:\n\n- CVE-2026-25833: mbedtls: buffer overflow in the `x509_inet_pton_ipv6()` function (bsc#1261476).\n- CVE-2026-25834: mbedtls: client accepts signature algorithm chosen by server even if not advertised in client hello\n  (bsc#1261477).\n- CVE-2026-25835: mbedtls: no pseudo-random number generator reseed when cloning an application (bsc#1261478).\n- CVE-2026-34874: mbedtls: NULL pointer dereference in distinguished name parsing (bsc#1261469).\n","status":"published","published":"2026-06-02T09:29:38Z","modified":"2026-06-04T09:00:10.048054471Z","updated_at":"2026-11-02T16:58:41.885092Z"},{"id":"openSUSE-SU-2026:21144-1","title":"Security update for mbedtls","description":"This update for mbedtls fixes the following issues:\n\nChanges in mbedtls:\n\n- Update to 3.6.6 (LTS maintenance update from 3.6.1); security fixes\n  accumulated across the 3.6.2-3.6.6 releases:\n  * CVE-2024-49195 (boo#1231708): buffer underrun in pkwrite when\n    writing an opaque key pair\n  * CVE-2025-27809 (boo#1240051): certificate verification accepted\n    arbitrary hostnames\n  * CVE-2025-27810 (boo#1240052): possible authentication bypass on\n    failed memory allocation / hardware errors\n  * CVE-2025-47917 (boo#1246783): misleading memory management in\n    mbedtls_x509_string_to_names()\n  * CVE-2025-48965 (boo#1246784): NULL pointer dereference after\n    mbedtls_asn1_store_named_data()\n  * CVE-2025-49087 (boo#1246973): timing side channel in PKCS#7\n    padding removal\n  * CVE-2025-49600 (boo#1245808): unchecked return values in LMS\n    verification allow signature bypass via fault injection\n  * CVE-2025-49601 (boo#1245809): out-of-bounds read in\n    mbedtls_lms_import_public_key()\n  * CVE-2025-52496 (boo#1245810): race in AES-NI support detection can\n    lead to AES key extraction or GCM forgery\n  * CVE-2025-52497 (boo#1245811): one-byte heap underflow when parsing\n    PEM-encrypted material\n  * CVE-2025-54764 (boo#1252341): timing attacks in RSA operations\n  * CVE-2025-59438 (boo#1252454): padding-oracle attack via timing of\n    cipher error reporting\n  * CVE-2026-25833: PSA RNG state duplicated across fork()\n  * CVE-2026-25834: TLS 1.3 HelloRetryRequest man-in-the-middle\n    session-resumption downgrade\n  * CVE-2026-25835: RNG state duplicated when application/VM state is\n    cloned\n","status":"published","published":"2026-06-22T13:34:13Z","modified":"2026-06-30T18:24:45.186057867Z","updated_at":"2026-11-02T16:58:41.885092Z"},{"id":"SUSE-SU-2026:1952-1","title":"Security update for ovmf","description":"This update for ovmf fixes the following issues\n\n- CVE-2026-25833: mbedtls: buffer underflow in x509_inet_pton_ipv6() (bsc#1261476).\n- CVE-2026-25834: mbedtls: Algorithm downgrade vulnerability (bsc#1261477).\n- CVE-2026-25835: mbedtls: PSA random generator cloning (bsc#1261478).\n- CVE-2026-34874: mbedtls: NULL pointer dereference when setting a distinguished name (bsc#1261469).\n\nChanges for ovmf:\n\n- Update mbedtls to 3.6.6.\n","status":"published","published":"2026-05-18T07:52:55Z","modified":"2026-05-19T08:45:09.132612186Z","updated_at":"2026-11-02T15:54:01.610851Z"},{"id":"SUSE-SU-2026:21440-1","title":"Security update for ovmf","description":"This update for ovmf fixes the following issues:\n\n- CVE-2026-25833: mbedtls: buffer overflow in the `x509_inet_pton_ipv6()` function (bsc#1261476).\n- CVE-2026-25834: mbedtls: client accepts signature algorithm chosen by server even if not advertised in client hello\n  (bsc#1261477).\n- CVE-2026-25835: mbedtls: no pseudo-random number generator reseed when cloning an application (bsc#1261478).\n- CVE-2026-34874: mbedtls: NULL pointer dereference in distinguished name parsing (bsc#1261469).\n","status":"published","published":"2026-04-24T13:08:28Z","modified":"2026-05-05T18:23:54.603701Z","updated_at":"2026-11-02T15:54:02.312556Z"},{"id":"SUSE-SU-2026:21981-1","title":"Security update for ovmf","description":"This update for ovmf fixes the following issues:\n\n- CVE-2026-25833: mbedtls: buffer overflow in the `x509_inet_pton_ipv6()` function (bsc#1261476).\n- CVE-2026-25834: mbedtls: client accepts signature algorithm chosen by server even if not advertised in client hello\n  (bsc#1261477).\n- CVE-2026-25835: mbedtls: no pseudo-random number generator reseed when cloning an application (bsc#1261478).\n- CVE-2026-34874: mbedtls: NULL pointer dereference in distinguished name parsing (bsc#1261469).\n","status":"published","published":"2026-06-02T09:29:38Z","modified":"2026-06-04T09:00:07.236788331Z","updated_at":"2026-11-02T15:54:02.654057Z"},{"id":"SUSE-SU-2026:22016-1","title":"Security update for ovmf","description":"This update for ovmf fixes the following issues:\n\n- CVE-2026-25833: mbedtls: buffer overflow in the `x509_inet_pton_ipv6()` function (bsc#1261476).\n- CVE-2026-25834: mbedtls: client accepts signature algorithm chosen by server even if not advertised in client hello\n  (bsc#1261477).\n- CVE-2026-25835: mbedtls: no pseudo-random number generator reseed when cloning an application (bsc#1261478).\n- CVE-2026-34874: mbedtls: NULL pointer dereference in distinguished name parsing (bsc#1261469).\n","status":"published","published":"2026-06-02T09:33:25Z","modified":"2026-06-09T18:24:27.804362044Z","updated_at":"2026-11-02T15:54:02.654057Z"}]}}