CVE-2020-12403

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-24. NVD baseline CVSS 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2%CVSS: 9.1Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
46(Track)
EG Risk 46/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
2%
EPSS %ILE
72%
KEV
Not listed

Published

May 27, 2021

Last Modified

November 21, 2024

Advisory Details (3)

Auto-updated Jul 18, 2026
Patch available. Sources: redhat.
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20230324-0006/
generic Patch Available

[SECURITY] [DLA 3327-1] nss security update

https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html
redhat Patch Available

1868931 – (CVE-2020-12403) CVE-2020-12403 nss: CHACHA20-POLY1305 decryption with undersized tag leads to out-of-bounds read

Affected: Red Hat Enterprise Linux 7

https://bugzilla.redhat.com/show_bug.cgi?id=1868931

Vendor Advisories for CVE-2020-12403(6)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(6)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatnss-softokn-0:3.44.0-9.el7_72021-03-30redhat
redhatopenshiftdo/odo-init-image-rhel7:1.1.3-22021-03-22redhat
redhatnss-softokn-0:3.36.0-7.el7_62021-03-16redhat
redhatnss-softokn-0:3.28.3-10.el7_42021-03-09redhat
redhatnss-0:3.53.1-17.el8_32021-02-16redhat
redhatnss-util-0:3.53.1-1.el7_92020-09-29redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 106 total refreshes for this CVE.

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Frequently asked(5)

What is CVE-2020-12403?
CVE-2020-12403 is a critical vulnerability published on May 27, 2021. 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.…
When was CVE-2020-12403 disclosed?
CVE-2020-12403 was first published in the National Vulnerability Database on May 27, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-12403 actively exploited?
CVE-2020-12403 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2% probability of exploitation in the next 30 days, which ranks it in the top 27.7% of all scored CVEs.
What is the CVSS score of CVE-2020-12403?
CVE-2020-12403 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2020-12403?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-12403, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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