CVE-2020-12403: mozilla nss Out-of-bounds Read
Vulnerability summary
CVE-2020-12403 is a critical (CVSS 9.1) Out-of-bounds Read vulnerability in mozilla nss. EPSS estimates a 1.54% chance of exploitation in the next 30 days, higher than 74.5% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 13 · Related 5Timeline
- 27-05-2021PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
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.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · AlpineEcosystem advisory · calculated9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- OSV · DebianEcosystem advisory · calculated9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS trend
Probability
1.54%
Chance of exploitation in the next 30 days
Percentile
75%
Versus all other CVEs
30-day change
0.00 pp
From 1.54% on 18-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Alpine1 product
- nss< 3.55-r0
Debian1 product
- nss< 2:3.55-1
Mozilla1 product
- nss< 3.55
Ubuntu1 product
- nss< 2:3.28.4-0ubuntu0.14.04.5+esm8 | < 2:3.28.4-0ubuntu0.16.04.14 | < 2:3.35-2ubuntu2.12 | < 2:3.49.1-1ubuntu1.5
4 vendors · 4 products
References
11 links- developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.55_release_notesREPORTRelease NotesVendor Advisory
