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.
総合評価: CVE-2020-12403 は中リスク（62.3/100）。CVSS 深刻度は重大。悪用される可能性が高い（EPSS 1.54%、72 パーセンタイル） 推奨対応: 影響資産を整理し、修補計画に組み込んでください。
リスクは変動します。再評価に基づき、本ページの表示内容を更新しています。
EPSS は日次で悪用されやすさの相対度合いを推定します。パーセンタイルは採点済み CVE の中での相対位置（高いほど相対的に深刻）を示します。
| # | 日付 | 旧 EPSS スコア | 新 EPSS スコア | Δ（新 − 旧） |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.72% | 1.54% | +0.82% |
| 2 | 2026-05-28 | 0.58% | 0.72% | +0.14% |
| 3 | 2026-02-24 | — | 0.58% | — |
EPSS の全履歴 （全 17 件）
この CVE の CVSS 指標。
| ベーススコア | バージョン | 深刻度 | ベクトル | 悪用しやすさ | 影響 | スコアの出典 |
|---|---|---|---|---|---|---|
| 9.1 | 3.1 | CRITICAL |
|
3.9 | 5.2 | [email protected] |
| 6.4 | 2.0 | MEDIUM |
|
10.0 | 4.9 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
critical | CVE-2020-12403: 1 source package rows (nss); 40 state rows across 10 repos (3.11-main, 3.12-main, 3.17-community, 3.18-community, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-community, edge-main); fixed 9, open 31. | https://security.alpinelinux.org/vuln/CVE-2020-12403 |
debian
|
not yet assigned | CVE-2020-12403 not yet assigned priority: Debian including 1 source packages (nss), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. | https://security-tracker.debian.org/tracker/CVE-2020-12403 |
gentoo
|
normal | CVE-2020-12403: 1 GLSA(s) (202008-08), 1 atom(s) (dev-libs/nss); latest impact normal. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-12403 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2020-12403 |
ubuntu
|
medium | CVE-2020-12403 medium priority: Ubuntu including 1 source packages (nss), 5 status rows across 5 suites (bionic, focal, trusty, upstream, xenial): released 5. | https://ubuntu.com/security/CVE-2020-12403 |
| URL | タグ |
|---|---|
| https://bugzilla.redhat.com/show_bug.cgi?id=1868931 | Issue Tracking Patch Third Party Advisory |
| https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.55_release_notes | Release Notes Vendor Advisory |
| https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html | |
| https://security.netapp.com/advisory/ntap-20230324-0006/ |