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01 Record

CVE-2021-23954

Using the new logical assignment operators in a JavaScript switch statement could have caused a type confusion, leading to a memory corruption and a potentially exploitable crash. This vulnerability

UnratedPUBLISHEDCNA: mozilla
CNA base scoreUnratedNo CNA CVSS vector

02 Description

Using the new logical assignment operators in a JavaScript switch statement could have caused a type confusion, leading to a memory corruption and a potentially exploitable crash. This vulnerability

03 Exploitation and scoring

Exploitation
Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
SSVC decision
Not assessed by CISA
EPSS probability
1.18% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 67.5% of scored records. A rank, not a probability.
NVD base score
8.8 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2021-02-26 02:10Z5 YR AGO
Last updated
2024-08-03 19:14Z2 YR AGO
Reserved
2021-01-13
Assigning CNA
mozilla
Record state
PUBLISHED
Severity
Not rated by the issuing CNA
CNA CVSS vector
Not published by the issuing CNA
Weaknesses
  • CWE-843Access of Resource Using Incompatible Type ('Type Confusion')Base
Data version
5.1
Document digest
2e402855b748d0c4a2c80fea4f5303d934a13df2ea699f6d486be1c3661bc5ea

05 Affected products

VendorProductVersionsPlatforms
MozillaFirefox< 85—
MozillaThunderbird< 78.7—
MozillaFirefox ESR< 78.7—

06 References

07 Fixed in

Arch Linux

  • firefox
    Fixed in 85.0-1
  • thunderbird
    Fixed in 78.7.0-1

Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.

Debian 12

  • firefox-esr
    Fixed in 78.7.0esr-1
  • thunderbird
    Fixed in 1:78.7.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • firefox-esr
    Fixed in 78.7.0esr-1
  • thunderbird
    Fixed in 1:78.7.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • firefox-esr
    Fixed in 78.7.0esr-1
  • thunderbird
    Fixed in 1:78.7.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 16.04 LTS

  • firefox
    Fixed in 85.0+build1-0ubuntu0.16.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 18.04 LTS

  • firefox
    Fixed in 85.0+build1-0ubuntu0.18.04.1
  • mozjs38
    No fix yet
  • mozjs52
    No fix yet
  • thunderbird
    Fixed in 1:78.8.1+build1-0ubuntu0.18.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 20.04 LTS

  • firefox
    Fixed in 85.0+build1-0ubuntu0.20.04.1
  • mozjs52
    No fix yet
  • mozjs68
    No fix yet
  • thunderbird
    Fixed in 1:78.7.1+build1-0ubuntu0.20.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 22.04 LTS

  • mozjs78
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.