{"id":"CVE-2020-12457","aliases":["DEBIAN-CVE-2020-12457","EUVD-2020-4768","GHSA-85m8-xxmw-3hpv","UBUNTU-CVE-2020-12457"],"status":"published","title":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS)...","description":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-10","score":0.01531,"percentile":0.74969,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-20","CWE-835"],"published":"2020-08-21T13:06:44Z","modified":"2026-10-26T12:01:33Z","fixes":[{"ecosystem":"Debian:12","package":"wolfssl","fixed_in":["4.5.0+dfsg-1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"wolfssl","fixed_in":["4.5.0+dfsg-1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.5.0+dfsg-1"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.5.0+dfsg-1"}]}]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.8+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.10.2+dfsg-2","3.12.0+dfsg-1","3.12.2+dfsg-1","3.13.0+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.0+dfsg-2","4.2.0+dfsg-1","4.2.0+dfsg-2","4.2.0+dfsg-3","4.3.0+dfsg-2"]}],"products":[{"vendor":"wolfssl","product":"wolfssl"}],"references":[{"url":"https://github.com/wolfSSL/wolfssl/pull/2927","tags":["x_refsource_MISC","x_transferred","Patch","Third Party Advisory","fix","report"]},{"url":"https://github.com/wolfSSL/wolfssl/releases/tag/v4.5.0-stable","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-12457"},{"url":"https://github.com/advisories/GHSA-85m8-xxmw-3hpv"},{"url":"https://security-tracker.debian.org/tracker/CVE-2020-12457","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2020-12457","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2020-12457","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2020-12457","description":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.","status":"published","published":"2020-08-21T13:06:44Z","modified":"2024-08-04T11:56:51.984Z","updated_at":"2026-11-02T14:35:52.925152Z"}],"euvd":[{"id":"EUVD-2020-4768","description":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.","status":"published","published":"2020-08-21T13:06:44Z","modified":"2024-08-04T11:56:51Z","updated_at":"2026-11-03T03:07:40.388635Z"}],"ghsa":[{"id":"GHSA-85m8-xxmw-3hpv","title":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS)...","description":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.","status":"published","published":"2022-05-24T17:26:17Z","modified":"2023-01-29T05:03:49Z","cwes":["CWE-20"],"updated_at":"2026-11-02T14:45:24.208268Z"}],"nvd":[{"id":"CVE-2020-12457","description":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.","status":"published","published":"2020-08-21T14:15:10.997Z","modified":"2026-06-17T02:51:50.63Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:06:13.05572Z"}],"osv":[{"id":"CVE-2020-12457","description":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.","status":"published","published":"2020-08-21T14:15:10.997Z","modified":"2026-10-20T10:51:06.699489279Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:44:14.034736Z"},{"id":"DEBIAN-CVE-2020-12457","description":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.","status":"published","published":"2020-08-21T14:15:10.997Z","modified":"2026-10-26T12:01:33.662000076Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:45:32.862554Z"},{"id":"UBUNTU-CVE-2020-12457","description":"An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.","status":"published","published":"2020-08-21T14:15:00Z","modified":"2026-04-22T12:27:59.825356Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:54:22.804634Z"}]}}