Search for vulnerabilities
Vulnerability details: VCID-g985-z4cb-wba7
Vulnerability ID VCID-g985-z4cb-wba7
Aliases CVE-2021-29955
Summary A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.)
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
System Score Found at
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
epss 0.00884 https://api.first.org/data/v1/epss?cve=CVE-2021-29955
cvssv2 2.6 https://nvd.nist.gov/vuln/detail/CVE-2021-29955
cvssv3.1 5.3 https://nvd.nist.gov/vuln/detail/CVE-2021-29955
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-10
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-11
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2021-29955
https://bugzilla.mozilla.org/show_bug.cgi?id=1692972
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23981
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23982
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23984
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23987
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-29955
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-4127
https://www.mozilla.org/security/advisories/mfsa2021-10/
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
CVE-2021-29955 https://nvd.nist.gov/vuln/detail/CVE-2021-29955
mfsa2021-10 https://www.mozilla.org/en-US/security/advisories/mfsa2021-10
mfsa2021-11 https://www.mozilla.org/en-US/security/advisories/mfsa2021-11
No exploits are available.
Vector: AV:N/AC:H/Au:N/C:P/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-29955
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-2021-29955
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 0.74467
EPSS Score 0.00884
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:47.828360+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2021/mfsa2021-10.yml 37.0.0