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CVE-2021-29955

MEDIUM
5.3
CVSS Score
Published: June 24, 2021 at 01:17 PM UTC
Updated: June 17, 2026 at 03:48 AM UTC
2 products affected across 1 vendorFirefoxFirefox ESR

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Severity
MEDIUM5.3
Exploit prediction
EPSS 1%

Description

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.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Firefox· Mozilla
95%
v < 87
Affected range stops below 87, so it looks safe — our inference, not a vendor statement
Affected range stops below 87.0, so it looks safe — our inference, not a vendor statement
Firefox ESR· Mozilla
95%
v < 78.9
Affected range stops below 78.9, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

x_refsource_MISCPermissions RequiredVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1692972
x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-10/
x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-11/

CVSS

5.3MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-74

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