{"id":"CVE-2020-12403","url":"https://www.cyber-defence.io/tools/cve/CVE-2020-12403","generatedAt":"2026-10-27T23:28:43.751Z","title":"When using multi-part Chacha20, it could cause out-of-bounds reads.","description":"A flaw was found in the way CHACHA20-POLY1305 was implemented in NSS in versions before 3.55. When using multi-part Chacha20, it could cause out-of-bounds reads. This issue was fixed by explicitly disabling multi-part ChaCha20 (which was not functioning correctly) and strictly enforcing tag length. The highest threat from this vulnerability is to confidentiality and system availability.","published":"2021-05-27T19:15:08.000Z","lastModified":"2026-06-17T02:51:46.000Z","status":"Modified","sourceIdentifier":"security@mozilla.org","cvss":{"version":"3.1","score":9.1,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H"},"cwe":["CWE-125"],"affected":["mozilla/nss"],"epss":{"score":0.01541,"percentile":0.74748,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (1.54%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1868931","tags":["Issue Tracking","Patch","Third Party Advisory"],"source":"security@mozilla.org"},{"url":"https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.55_release_notes","tags":["Release Notes","Vendor Advisory"],"source":"security@mozilla.org"},{"url":"https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html","source":"security@mozilla.org"},{"url":"https://security.netapp.com/advisory/ntap-20230324-0006/","source":"security@mozilla.org"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1868931","tags":["Issue Tracking","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.55_release_notes","tags":["Release Notes","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20230324-0006/","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2020-12403","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}