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Vulnerability details: VCID-55kj-h5g8-tqhj
Vulnerability ID VCID-55kj-h5g8-tqhj
Aliases CVE-2021-23977
Summary Firefox for Android suffered from a time-of-check-time-of-use vulnerability that allowed a malicious application to read sensitive data from application directories.*Note: This issue is only affected Firefox for Android. Other operating systems are unaffected.*
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (1)
System Score Found at
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23977
cvssv3.1 5.3 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 2.6 https://nvd.nist.gov/vuln/detail/CVE-2021-23977
cvssv3.1 5.3 https://nvd.nist.gov/vuln/detail/CVE-2021-23977
archlinux Medium https://security.archlinux.org/AVG-1600
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-07
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none

Vector: AV:N/AC:H/Au:N/C:P/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23977
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23977
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none

Exploit Prediction Scoring System (EPSS)
Percentile 0.58177
EPSS Score 0.00372
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:48.829415+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2021/mfsa2021-07.yml 37.0.0