{"cve":"CVE-2015-2721","nvd":{"published":"2015-07-06T02:00:49.283","modified":"2026-06-17T00:24:36.910","status":"Modified","description":"Mozilla Network Security Services (NSS) before 3.19, as used in Mozilla Firefox before 39.0, Firefox ESR 31.x before 31.8 and 38.x before 38.1, Thunderbird before 38.1, and other products, does not properly determine state transitions for the TLS state machine, which allows man-in-the-middle attackers to defeat cryptographic protection mechanisms by blocking messages, as demonstrated by removing a forward-secrecy property by blocking a ServerKeyExchange message, aka a \"SMACK SKIP-TLS\" issue.","cvss_v4":null,"cvss_v3":null,"cwes":["CWE-310"],"references":["http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00025.html","http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00031.html","http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00033.html","http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00034.html","http://lists.opensuse.org/opensuse-security-announce/2015-08/msg00021.html"],"products":["canonical:ubuntu_linux","debian:debian_linux","mozilla:network_security_services","novell:suse_linux_enterprise_desktop","novell:suse_linux_enterprise_server","novell:suse_linux_enterprise_software_development_kit","oracle:solaris","oracle:vm_server"],"source":"nvd","synced_at":"2026-10-19T20:36:40.444340523+00:00"},"epss":{"cve":"CVE-2015-2721","score":0.02825,"percentile":0.86596,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}