CVE-2020-12403
When using multi-part Chacha20, it could cause out-of-bounds reads.
Does this matter?
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.
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 3.1
- 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- EPSS
- 1.54% probability · 75th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-125
- Affected
- mozilla/nss
- Source
- security@mozilla.org
EPSS 1.5% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.redhat.com/show_bug.cgi?id=1868931Issue Tracking, Patch, Third Party Advisory
- https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.55_release_notesRelease Notes, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html
- https://security.netapp.com/advisory/ntap-20230324-0006/
- https://bugzilla.redhat.com/show_bug.cgi?id=1868931Issue Tracking, Patch, Third Party Advisory
- https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.55_release_notesRelease Notes, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html
- https://security.netapp.com/advisory/ntap-20230324-0006/
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.